[[caption-width-right:309:With adequate RagnarokProofing, a SealedBadassInACan is sure to awaken and heed the CallToAdventure.]]
[-[[caption-width-right:309:[[http://behance.vo.llnwd.net/profiles4/124029/projects/1498997/71721d881b1e958a7436ce72cdaff3b3.jpg Image]] by [[http://www.behance.net/gallery/Adventure-Concept-Art/1498997 Artur Sadlos]]]]-]

->"''To be fair, we don't invent them. We find them. They're gifts, Mr. Miles, from Those Who Came Before.''"
-->-- '''Warren Vidic''', ''VideoGame/AssassinsCreedI''

%% One quote is sufficient. Any extra quotes can go to its own subpage.

Beyond SchizoTech, beyond ScavengerWorld, there's Lost Technology.

[[{{Precursors}} The Ancients]] had some pretty ''[[OlderIsBetter neat]]'' gear. Robots, weapons, [[Franchise/TheHitchhikersGuideToTheGalaxy even the answer to The Ultimate Question of Life, The Universe, and Everything.]] [[InWorkingOrder Easy to use]], little or no maintenance required, and [[RagnarokProofing after thousands of years of neglect often still in perfect working order]]!

...oh yeah, and this technology completely and utterly destroyed the Ancients [[AfterTheEnd and most of the world]] with it. But that doesn't stop the villains (or the heroes) from wanting to get some for themselves by pillaging an AdvancedAncientAcropolis. Usually, said Lost Technology then tries to destroy the world ''again.'' Some, but not all, heroes are smart enough to try to keep people away from the stuff.

Occasionally the good guys need Lost Technology to combat ancient evils that have arisen again (or villains who have acquired Lost Technology of their own). They usually use it as best they can, despite {{Black Box}}es. Still, they suffer from LowCultureHighTech.

It is similar to ImportedAlienPhlebotinum, with the catch that the current population comprises the survivors or replacements of [[AndManGrewProud an age that fell due to its arrogance, war, or some other catastrophe.]]

May also show up in the guise of Lost Magic in fantasy settings. Often a consequence of NoPlansNoPrototypeNoBackup. Also see SufficientlyAdvanced and PointlessDoomsdayDevice. Compare BambooTechnology. A subtrope of OlderIsBetter. Frequently overlaps with SufficientlyAdvancedBambooTechnology. May lead to an ArchaeologicalArmsRace.


[[folder:Anime and Manga]]
* In ''Anime/MazingerZ'', the plot is set in motion when BigBad Dr. Hell finds an army of giant robots in the underground mazes of the Greek island his archaeological expedition was researching, belonging to the lost Mykene civilization. Instantly he decides to seize that technology to further his goals of world domination. Too bad to him -and the world- [[Anime/GreatMazinger the legitimate owners of that technology were still around]]. In one of the ''Anime/UFORoboGrendizer'' mangas, Lost Technology had an important -and dire- role.
* In ''Anime/KotetsuJeeg'', Dr. Shiba finds several ancient mysterious magical artifacts and hieroglyphs during an archaeological expedition. His findings provide evidence of the ancient lost kingdom of Yamatai that thrived in south of Japan has survived, and its Queen Himika is preparing to invade Japan. Of course, his reaction was using that lost technology to get a countermeasure ready (i. e., turning his eldest son into a cyborg capable transforming into a HumongousMecha).
* In ''Anime/TheMysteriousCitiesOfGold'', the little bits of surviving technology from the Mu Empire are this, including a solar powered warship that shoots lasers, [[HollywoodDensity a solid gold airplane]], and ''[[spoiler:a nuclear reactor]]''. Fighting against [[SchizoTech Spanish galleons and]] [[{{Mayincatec}} Mayincatecs]] with spears.
* TheCity in ''Manga/{{Blame}}'' is so ''[[UnnecessarilyLargeInterior immeasurably vast]]'' that "lost" technology is positively ubiquitous, which isn't surprising, considering that the mega structure was built over the span of thousands of years and encompasses most of the solar system. For a more obvious example, Killy's [[WaveMotionGun weapon]] is revealed to be an ancient and legendary piece of technology that nobody has been able to replicate. [[DullSurprise He is mildly shocked to learn this]].
* Keeping people from (while recklessly getting into) the stuff is a major premise of ''Anime/GalaxyAngel'', which is called Lost Technology in the series. The serious ''VideoGame/GalaxyAngel'' gameverse has it in droves, but replace backtalking missiles with, say, dangerous ones.
* The Demon God Androids, the Eye of God "Death Star", the Trigger of Destruction battleship, etc. etc. from ''Anime/ElHazardTheMagnificentWorld.''
* ''Franchise/MagicalGirlLyricalNanoha'' has a ton of this stuff, and it's always a major part of whatever crisis the main characters are facing. Magic was specifically nurtured and developed in order to handle the multiple times someone finds a "Lost Logia" and accidentally (or intentionally) pushes the "destroy planet" button. In ''[[Anime/MagicalGirlLyricalNanohaStrikers StrikerS]]'', it's shown that there are Lost Logia that are safe enough to legally be sold in auctions.
* Showed up often in ''Manga/SorcererHunters''.
* The demi-armors from ''Anime/MazeMegaburstSpace''.
* The eponymous airships in ''Anime/{{Simoun}}'' are so far lost that their origin isn't clearly remembered. [[spoiler:Knowledge of how to use them is only regained through time travel.]]
* ''Anime/{{Texhnolyze}}''. The technology is only lost to the population of Lukuss - the Class and the Theonormals never lost it.
* The doll Emily in ''Anime/StrainStrategicArmoredInfantry'' turns out to be Lost Technology with [[PoweredByAForsakenChild dubious origins]].
* An ancient war machine forms a important part of the plot of ''Manga/NausicaaOfTheValleyOfTheWind''.
* Due to citywide amnesia, the megadeuses from ''Anime/TheBigO'' are Lost Technology despite being little more than 40 years old.
* Boson Jump and Phase Transition technology in ''Anime/MartianSuccessorNadesico''.
* In ''Manga/MurderPrincess'', the Lost Technology is actually ''called'' Lost Technology, proper noun. [[spoiler:All of the world's "magic" and monsters, as well as the heroine's two companions, were born from Lost Technology, and when its "central processing unit" is destroyed [[NoOntologicalInertia so is everything it created]].]]
* This is the whole basis of the manga ''Manga/SixSixSixSatan'' (a.k.a. ''O-Parts Hunter'') with [[spoiler: the most ultimate of lost technology able to restart the universe itself.]]
* ''LightNovel/TrinityBlood''. Not only is it actually called Lost Technology but they even heavily analogize Lost Technology to magic by giving it mystical references.
* The technology of Laputa in ''Anime/CastleInTheSky''. Unusually, it did not destroy them; they voluntarily threw it away because it was alienating them from [[{{Arcadia}} the earth]].
* The main theme of ''Anime/TurnAGundam''. To fight back against the alien humans of the Moon Race, Earth (which appears to have somehow gone back to the Victorian era) starts digging up old mobile suits and battleships it finds. Turns out [[spoiler: we're seeing the end of all the then known Gundam timelines. The Turn A was so powerful it sent humanity effectively back to the stone age, with only the Moon Race retaining video documentation of what happened.]]
** Also used as the plot for the more kid aimed spin off ''Musha Generation'', alabeit with the mecha now super deformed, more fantasy elements to the cast and the overall theme being the way of the samurai.
* ''Anime/MobileSuitGundamAGE'' has a similar mechanic with the "cursed treasure", the EXA-DB. Centuries before the series, a united human race vowed to give up war and destroyed all their advanced weapons. All information regarding how to create them was placed in a massive database... and lost. [[spoiler:Vagan's mobile suits are so powerful because they discovered a small fraction of the EXA-DB and based their military tech on it. Both sides are hunting for it, knowing that the lost military tech stored within would easily decide the victor in their generation-spanning war. It briefly appeared in a side manga called ''Memories of Sid'', found by the Bisidian Space Pirates, who got trounced by its automatic defense system Sid, and they have since lost it again.]]
* In ''Manga/{{Trigun}}'' they literally call the [[OrganicTechnology Plants]] "[[GratuitousEnglish Lost Technology]]". The Plants are like power plants, they produce energy that allows humans to survive on the planet Gunsmoke. The Plants were invented on another, now mostly mythical planet (Earth), and with one exception the knowledge of how and why the Plants work is completely forgotten.
* ''Anime/GunXSword'' is a SpiritualSuccessor to ''Trigun'' and also uses this. Two examples are the feuding sisters [[spoiler: who turn out to be clones whose father actually saw them as experiments not children, and neither they nor the other characters know what the word clone means]] and that [[WhatDoYouMeanItsNotSymbolic cross puzzle Van tries to open]] which turns out to be an electromagnetic shield for his mecha.
* ''Anime/LostUniverse'' with its Lost Ships and Psi Weapons. Depending on the Fanon accepted the Lost Technology may be actual, magical gods and demons that have chosen to disguise themselves in the form of technology.
* In ''Manga/BreakBlade'', the hero Rygart's mecha or err ''Golem'' is not made of quartz like everyone else's, oh no, his is an ''unholy'' fusion of cheap metal, oil and he is apparently the only one who can use it -- viceversa goes for the quartz golems. Besides being this trope it is also faster and stronger than anything made from quartz.
* In ''Anime/SoundOfTheSky'' only 10 [[SpiderTank Tamekicaduchis]] are left, and it takes a TeenGenius to make one operational.
* In ''Manga/FairyTail'', "Lost Magic" is, according to Master Hades [[spoiler:the former master of Fairy Tail]] of Grimoire Heart, the magic closest to the source of all magic in their world [[spoiler:which he believes is connected to Black Mage Zeref]]. The strongest members of his guild, [[NamesToRunAwayFromReallyFast the Seven Kin of Purgatory]], are armed with Lost Magic and are extremely powerful.
* In ''Anime/HeatGuyJ'', humanity has gone several steps back technology wise, after a calamitous war. The most advance technology is being controlled and maintained by an apparently benevolent group known as the Celestials. In fact a number of laws were enacted after the war to prevent humans from regaining some of the more destructive technologies, notability research into androids has been outlawed (with some exceptions) and the only android allowed within city limits or populated areas is J.
* Lost Technology is both the central MacGuffin and the enabling device in ''Manga/{{Spriggan}}'', which revolves around an archeological arms race between cold war powers, a few secretive fringe groups, and the ARCAM foundation, which seeks to secure (or if that's not possible, disable beyond repair or useful R&D) all "Out-of-Place Artifacts", or "[=OOPArts=]", until such time as they feel that the rest of humanity is ready to use them responsibly.
* ''{{Anime/Diebuster}}'':
** Warp technology was purposefully suppressed after humanity gave up trying to explore the galaxy thousands of years ago, to the point that nobody even knows the first principles behind it. And then, of course, there's [[spoiler:Nono]].
** The giant space habitat where Jupiter is supposed to be. In the episode where it appears, the characters mention that it used to be a space battleship - and indeed, closer examination by a viewer who had seen ''Gunbuster'' will reveal that it's actually the Eltreum, the [[MileLongShip 70 km]] [[TheBattlestar white flagship]] that led humanity's final assault on the galactic core at the end of ''Gunbuster''. Since then, it had its degeneracy reactor destroyed and the hull hollowed out to create a space habitat instead of being scuttled and dismantled for the simple reason that the outer armor is [[MadeOfIndestructium made of a material not even antimatter pair-annihilation could damage]].
* Invoked with the Zentraedi of ''Anime/{{Macross}}'' and ''Anime/SuperDimensionFortressMacross''[='s=] English adaptation ''Anime/{{Robotech}}'', who know absolutely nothing about building or repairing their various technologies. It turns out that this is a deliberate ploy on the part of their creators (the Protoculture in ''Macross'' and the Robotech Masters in ''Robotech'') to ensure that the Zentraedi must always depend on them to repair and replace used ammunition and broken parts and thus prevent a rebellion. While it works for the Robotech Masters (as Dolza, commander of the Zentradi, ''did'' want to rebel according to the ExpandedUniverse but knew he had no chance due to that factor), the Protoculture ended up exterminated [[GodzillaThreshold when they were forced to deactivate the]] ''[[GodzillaThreshold other]]'' [[GodzillaThreshold safeguard]] and couldn't reactivate it fast enough once the danger was over.
* ''Anime/PanzerWorldGalient'': Ancient war machines and weapons were buried everywere in planet Arst. [[BigBad Marder]] dug up tons of ancient technology to arm his army, and LaResistance tried to find and unearth best weapons to fight him with. The titular HumongousMecha was one of those weapons found by a rebel settlement.

[[folder:Comic Books]]
* One of the [[SarcasmMode brilliant]] ideas of the [[Fracnhise/GreenLantern Guardians of the Universe]] was to set up a civilization, the Psions, set up like this by design. They hoped that by seeding their planet with technology and sealing them off, they would slowly grow and understand the immeasurably powerful tech scattered across their world. While they did grow for a bit, this started a ViciousCycle in which they rise to a great level of technical skill, then realize their entire world was custom-made as an experiment, realize the truth of their farce of a culture, nuke themselves into the Stone Age in a fit of despair, and the cycle starts again. Worse yet, this culture has sent them into a spiral of abuse against other species, creating a race of {{Mad Scientist}}s.

[[folder:Fan Works]]
* In the ''Fanfic/TriptychContinuum'', the Discordian era destroyed virtually all records and artifacts from before that era. Every once in a while, someone manages to turn up a bit of lost technology, which are all incredibly valuable because they are too complicated to be reproduced and too rare to be disassembled and examined to even try. [[spoiler: In ''A Mark of Appeal'', it is revealed that the Sun and the Moon are both products of the lost ancient civilization.]]
* In the ''Fanfic/PonyPOVSeries'', technology from the Golden Age (MLPT Era) has been found, but ponies aren't certain how it works or what it is. Twilight and Luna eventually decide to help with recovering it now that Ponykind is ready to utilize it properly.

* In Creator/JRRTolkien's universe, older technology is always superior to newer technology, since the original crafts and techniques were largely perfect and Tolkien's universe's history is essentially a process of ''forgetting'' (losing) those crafts and techniques, not discovering better ones.
** ''Literature/TheSilmarillion'' states that the people of the First Age built an elven ship made of "mithril and elven-glass" that could travel both through the sky and through the Outer Void (outer space). This was the ship that Earendil used during the War of Wrath - it was not referred to in technological terms, but as a conventional ship that through divine power could also fly in the heavens.
** ''Literature/TheHistoryOfMiddleEarth'': In early versions of the stories, when Morgoth destroyed Gondolin, the great Elven city hidden in the mountains, he crossed the peaks with metal troop carriers that had fire in their bellies (i.e. engines). In the Second Age, the Númenóreans are said to have had ships that moved against the wind, with weapons that could "fire darts across an ocean." One version of the legends says that the Númenóreans in exile even managed to build aircraft in a futile attempt to escape the newly round world.
* Both sides of conflict in ''Literature/{{Safehold}}'' series have access to it, although only one knows about it. Main character, Merlin, is piece of Lost Tech himself - PICA, the implacable android with human memory. In his stock he has ultimate spying bugs, invisible recon machines, laser guns and assault crafts. His enemies, the church, have almost-living building, the Temple, and KillSat ''Rakurai''.
* In [[Creator/IsaacAsimov Asimov's]] ''Literature/{{Foundation}}'' novels, most of the galaxy loses its tech when the Empire collapses; the Foundation preserves, improves and reintroduces it. In the later novels, [[spoiler: sentient robots]] are a lost technology universally believed to be mythological, until the heroes meet the [[LastOfHisKind last surviving one]] in the final pages of the last book. In the ''first'' novel (specifically in ''The Mayors'') an old Imperial warship from the height of the Empire serves this purpose -- the Foundation may have the ''theoretical'' know-how to make such a ship, but since it is built on an absurdly large scale for their resources (the warship outmasses the ''entire'' Anacreonian navy, the largest navy in the region, and Terminus barely has any metals) they wouldn't, so it is still of interest to their engineers -- and of course the sheer power of the ship means that any local navy in possession of it, once repaired, would have a significant advantage over any other...
* Much of the phlebotinium in the ''Literature/MortalEngines'' series comes in the form of lost technology.
* Creator/TerryPratchett's ''Literature/{{Discworld}}'' novel ''Discworld/{{Thud}}'' introduced Lost Technology in the form of "Devices", mysterious magical/technological devices found and utilized by the dwarfs. Two examples are a inch-wide cube that functions as an indestructible audio recording device activated by voice commands and in some cases allegedly containing millions of years worth of sound. And something which is described as simply two blocks with some sort of bearing between that causes them to rotate in opposite directions. Forever and no matter how strong a force is used to try and hold them. Basically an infinite mechanical engine that can power anything on nothing. They are found so deep underground that it seems likely they were there when the world was constructed.
* Lost technology and the ruins of long lost high-tech civilizations turn up in the ''Literature/DyingEarth'' novels (and the fantasy RPG) by Jack Vance, as well as in several of his other short stories (both fantasy and science fiction).
* ''Literature/TheReynardCycle'': The crew of the Quicksilver encounter robots and electric lamps while in Carcosa. They interpret both to be the product of dark sorcery.
* There are hints of a previous, lost technological civilization in some of the ''Literature/{{Shannara}}'' novels, a fantasy series by author Creator/TerryBrooks. In ''Sword of Shannara'', the characters are told the civilisation destroyed itself with powerful weapons, and encounter a mutant-cyborg monstrosity in a ruined city. This aspect is not played up so much in the later novels, although the BigBad in one is an AI from the old world.
** Brooks is currently linking this to his Urban Fantasy series ''Literature/TheWordAndTheVoid'': ''Literature/TheGenesisOfShannara'' series is set AfterTheEnd of ''Word/Void''.
** The "Genesis of Shannara" series openly reveals that [[spoiler: the "lost technological civilization" is basically our world about a century in the future. The ruined landscape in which is takes place is the continental USA, the Elves live in an Oregon river valley and forest, and the final destructive event that triggers the cataclysm that re-shapes the world is when an insane US military officer trapped within a nuclear missile command bunker in North Dakota years after the Great Wars took place decides to launch the remaining US nuclear [=ICBMs=] (inter-continental ballistic missiles) on a whim.]]
* Creator/RobertJordan's ''Literature/TheWheelOfTime'' series heavily plays the Lost Magic angle up, stocking the world full of unknown thousand-year-old devices mostly in working order, sometimes harnessed and sometimes just accidentally triggered. The Hero is given glimpses into the pre-cataclysm world, as well. The "Age of Legends" was a personification of a CrystalSpiresAndTogas world, complete with [[spoiler: advanced flying machines and car-equivalents, genetic engineering, universal peace, high-quality medicine - you get the idea. Think an almost ideal peaceful, futuristic society aided and abetted by widespread magic and Magitek.]]
* Valyrian steel in ''Literature/ASongOfIceAndFire'', and though not really technology, in some weird manner, dragons.
** Valyrian steel is a fantasy counterpart to a [[TruthInTelevision real-world]] "lost" technology: Damascus steel.
** Also, the techniques used to raise the Wall, a seven-hundred foot tall wall of ice spanning a continent, built eight thousand years before the series takes place. Lord Commander Mormont said that unlike the hundred of previous commanders, he is the first one under whose rule it shrunk. The others always left it at least a couple meters higher. I.e. the wall was not built as it was at a single point in the past, it got bigger over thousands of years of labour. And the techniques are also presented - rocks and wooden beams and earth then covered in water that freezes into ice, pretty primitive though effective. Kind of an analogue to real-life pyramids, which many people also think to have been impossible to build at the time. And the "barrier" that stop the white walkers is more an instance of The Magic Goes Away, not technology, altough knowledge lost nevertheless.
* In Creator/StephenKing's ''Franchise/TheDarkTower'' series, Roland's world is littered with remnants of the super-advanced technology of the "Great Old Ones", including artificial intelligence, robots, and advanced weaponry. Elements of this technology frequently become central drivers of the plot.
* Lost Technology - Lost Magic version in the Literature/{{Deryni}} works:
** Deryni went from having thriving Healer schools and a regular cadre of Healers as part of society to no Healers in the whole of Gwynedd, with a very slight comeback (a handful of untrained Healers flying by the seat of their pants) two centuries later. Arcane knowledge generally is hidden away and /or lost, with traces gradually coming to light.
** Camber and his family circle also investigate more ancient ancestors Orin and Jodotha, as well as a strange altar with black and white cubes (akin to Wards Major) showing patterns they've never seen, much less used. Testing shows one of the patterns makes the altar drop into the floor to reveal a secret room beneath it.
* In ''Literature/SecondApocalypse'', there is the Tekne, the highly advanced technology of the alien Inchoroi race (including beam weapons and highly capable, sophisticated genetic engineering). The remnants of the [[AlienInvasion Inchoroi]] are largely ignorant of how their technology works, and use it in a black box, "trial-and-error" fashion.
* An ancient galaxy-spanning Internet exists in Creator/VernorVinge's ''Literature/AFireUponTheDeep'', with all the associated dangers such as viruses, translation errors, and propaganda. The novel is about what happens when a malevolent power, the Straumli Perversion, is [[SealedEvilInACan released from one of these archives]] by a team of archaeologist programmers.
* The stagnant remnants of a world-spanning autocracy that has frozen its culture for tens of thousands of years meets its comeuppance in the form of a one-way time traveller and his knowledge in another Vinge story, "The Peddler's Apprentice". His list of tricks consists of a self defense gadget, and the uplink codes to the array of spy and killsats left behind by Sharn, the "crystal city" the Kingdom of Fyffe devolved from.
* In a ''Series/StarTrekDeepSpaceNine'' novel, the crew of the ''Defiant'' runs across a world that was essentially SET UP this way as an experiment. A highly-advanced culture dropped off a whole bunch of their babies on a planet with tons of small, hi-tech devices scattered all over the place and sat back to see what would happen. The result is a people who are so dependent on technology they don't understand that they're royally screwed when the batteries go dead.
* In Creator/AynRand's ''Literature/{{Anthem}}'' Lost tech includes a subway system and an abandoned house.
* The series ''Literature/TheGeneral'', by Creator/DavidDrake and Creator/SMStirling (later, Creator/EricFlint steps in for Stirling), has a Lost Technology computer providing information for a planet at a development stage akin to the UsefulNotes/AmericanCivilWar on Earth, to eventually rebuild interstellar travel over a millennium after it was lost due to a galactic civil war.
* The titular quest in ''Hiero's Journey'' is about a search for lost computer technology in an AfterTheEnd world.
* T. E. Bass' ''Half Past Human'' depicts an Earth about 3000 years in our future, where humans have devolved into a four-toed variety (called the Nebish) and technology appears to have declined as well (although it's still higher than ours). There are two instances of Lost Technology in this novel, both owned by (and planted to assist) the few remaining five-toed outcasts; one gets dismantled by Nebish technicians, who fail to recognise it as a Class 6 cybernetic device, since it's small and portable and their understanding of Class 6 cybers is that the brain case alone would weigh over two tons.
* The city of Diaspar in Creator/ArthurCClarke's ''Literature/TheCityAndTheStars'' (a novel-length re-working of his earlier novella ''Against the Fall of Night'') is composed of technology that no one living understands any longer; but which is all fully automated and self-repairing. Somewhat subverted in that the computer that maintains the city, including the inhabitants -- who are cloned reincarnations of the original population with memories of all their incarnations stored in the computer -- could conceivably produce new inhabitants with the requisite memories. The technology necessary for space travel, on the other hand, had been deliberately purged both from the city computer's memory, and the records of the telepathic inhabitants of the pastoral city of Lys; and the populations of both cities had developed a phobia of space travel, with a powerful [[spoiler: and completely wrong]] mythology justifying their fear.
* In the ''TabletopGame/{{Warhammer 40000}}'' novel ''[[Literature/GreyKnights Dark Adeptus]]'', [[spoiler: Magos Antigonus]] is able to be NotQuiteDead thanks to some hitherto-unknown tech he finds shortly before he gets killed. The [[spoiler: Father of Titans]] is also shown to be comprised of tech that its copiers cannot replicate fully.
* Creator/LarryNiven's ''Literature/{{Ringworld}}'' and everything on it.
** There are actually a couple of examples in these stories. The inhabitants of the Ringworld have lost the technology to build or repair it (mostly; the [[spoiler: Protector]] builders left a couple of caches behind, and ensured that anyone who finds them will be smart enough to figure out how to use them). And then there's the City Builder culture, which was a bit below the tech level required to construct the place (or understand it, demonstrated by the fact that [[spoiler: they dismantled the stabilization system]]), which collapsed when [[spoiler: the Puppeteers destroyed their superconductors]], but which left bits and pieces of equipment based on different technology lying around, some of which still work.
* Another Niven example (this time with Creator/JerryPournelle as co-author): ''Literature/{{Footfall}}'' has the fithp: aliens capable of interstellar travel because a predecessor species on their homeworld left instructions behind. They've managed to decode the instructions so they have a (slightly) higher tech level than humans do, but they follow the instructions by rote as opposed to really ''understanding'' it.
* The technology of the various [[{{Precursor}} Forerunner]] races in Creator/AndreNorton's science fiction novels.
* In Jasper Fforde's ''Literature/ShadesOfGrey'' technology hasn't been lost so much as deliberately purged by a series of "Leapbacks". Some is still reserved for the government resulting in SchizoTech.
* The Literature/LiadenUniverse has "[=OldTech=]", Clarkian technology from the waning days of the previous universe (as seen in ''Crystal Soldier'' and ''Crystal Dragon'') and the early days of the present universe. Much of it was designed by or derived from tech designed by the Sheriekas, the evolved transhumans responsible for rendering that universe inhospitable to ordinary human life, and it can often carry their malign influence. One of the primary missions of the Scouts is to sequester or destroy any remnants of that technology that still exist, whether harmful or not, as well as research it to try to derive safe versions. This can sometimes bring them into conflict with others—such as Uncle or Clan Korval—who take a more enlightened stance toward using that technology. Likewise, the Department of the Interior recognizes the inherent advantage in having as much [=OldTech=] as they can.
* The setting of ''Aestival Tide'' by Elizabeth Hand is a city run entirely on forgotten technology, which is slowly failing and actively crumbling under its own weight since no one remembers how to control it.
* Elderglass from the Literature/GentlemanBastard series.
* The Deathly Hallows in ''Literature/HarryPotter''. Each of them is a one-of-a-kind artifact with power that laughs in the face of all conventional magic: the Elder Wand when wielded by its rightful owner is powerful enough to repair other wands (which Ollivander believed was impossible) with a simple Repairing Charm, the Resurrection Stone can summon a bonafide shade from the afterlife (even this much shouldn't be possible), and the Invisibilty Cloak's power doesn't vanish with time (all other Cloaks eventually run out of juice). Attempts to recreate the Hallows have all ended in failure. Even the Elder Wand -- wandmakers know that it's made out of elder wood and has a thestral hair core, but can't create another wand with its power even with those components available. The Hallows are so powerful and mysterious that one legend claims that ''Death itself'' created them.
* ''The Empire of the East'' and the ''Literature/BookOfSwords'' are set in the distant future of earth, after the collapse of technological civilization and the rise of magic. In ''Empire'', however, [[TheMagicComesBack Technology Comes Back]], or starts to, at any rate. The discovery of some old technological devices, including an atomic-powered battle tank, plays a major role in the story.
* In the ''Literature/{{Destroyermen}}'' series, the Americans lose access to a lot of their technology and are forced to start from scratch, with only each human's understanding of science to help them acquire similar results. Much of their manufactured ammunition and more modern technology that DID survive has been altered so much that numerous aspects of the original designs have been lost for the sake of ease of manufacture.
* Subverted in the Literature/{{Emberverse}} series: the lost technology won't even ''function'' in the post-Change world, although some specialized items manufactured using pre-Change techniques can be repurposed (''e.g.'', truck suspension springs to power ballistae and heavy catapults, precision-machined gears from automobiles being used in wind- and water-driven machinery, etc.) Spare parts and raw materials salvage is a major preoccupation (and source of wealth) for many communities.
* The BigBad in ''Literature/TheChroniclesOfPrydain'', Arawn used to travel the continent, stealing and hoarding magical devices and other more advanced technologies. Somehow he ended up also stealing the knowledge of the making of such devices, such that he sits on a treasure trove of Lost Technology, while the rest of the population wallows in ignorance.
* ''Literature/{{TheTripods}}'': the humans on Earth have lost all knowledge of scientific advancements since, essentially, Faraday's work on electromagnetic induction; steam power is used almost exclusively as the primary non-human/animal motive energy source. One of the characters [[spoiler:has no idea that he's passing by an electrical substation because he has no idea what a volt is.]]
* Creator/AlastairReynolds:
** In the ''Literature/RevelationSpaceSeries'', a civilization-wide cataclysm known as the Melding Plague - a [[TheVirus alien nanotechnologic virus]] which assimilates any other nanotechnology it contacts - caused the collapse of virtually all manufacturing facilities, most of which were located in the Glitter Belt (Now known as the Rust Belt) around Yellowstone. Humanity still knows how to make the technology, but it is impossible for it to built due to the lack of a manufacturing base, and the risk of the remaining strains of Plague corrupting it. Only the [[TransHuman Conjoiners]] were unaffected by the Plague, due to their extreme isolation. [[MileLongShip Lighthuggers]], the only form of interstellar travel, became this when the Conjoiners stopped building the ships; only the Conjoiners knew how to build the [[ReactionlessDrive Conjoiner Drive]] (and only they had the [[spoiler:[[BrainInAJar resources]]]]), and any attempt to reverse-engineer a Conjoiner Drive would result in a apocalyptic explosion as the drive's propulsion unit would collapse itself. In the modern age, Lighthuggers are priceless and are fiercely defended by their crews, the [[CyborgHelmsman cybernetically enhanced Ultranauts]].
** In ''Literature/TerminalWorld'', the technology behind Spearpoint - the last human city that [[StarScraper rises kilometers into the sky]] - has been lost even to the highest levels, where reality's EnforcedTechnologyLevels is at its weakest and technology borders on magic. Nobody knows how it was made, and what its original purpose was.
** ''Merlin's Gun'', humanity's tech base has steadily regressed under the relentless assault of the AbsoluteXenophobe Huskers. When Merlin rescues a human in a stasis pod after living in the black for hundreds of years, he notes how primitive the technology has become. On the other hand, the computer tech has progressed far beyond Merlin's; the rescuee's VirtualGhost effortlessly slips into Merlin's computer system.
* Creator/RobertAHeinlein's Future History has space travel becoming one, though rediscovered later.
* Plenty of {{Precursor}} technology is found throughout ''Literature/TheHistoryOfTheGalaxy'' books. The most jarring examples are a DysonSphere built by the [[BeePeople Insects]] and a giant supercomputer in space built by the [[StarfishAliens Logrians]], composed of tiny crystals, each of which is in itself a computer more powerful than anything humans have. What do the humans use with the giant supercomputer? Turn it into the replacement hub for their [=InterStar=] network. Yes, they take an advanced alien computer and use it as an Internet server with the tasks mainly limited to routing signals. There are also Logrian gravity generators that can bend light in such a way as to keep a whole star cluster hidden for millions of years. Humans adapt them as DeflectorShields for SpaceFighters.
** Note that most Insects and Logrians have been slave races to the Harammins for so long that they have forgotten how this technology works.
** A number of novels also focus on [[LostColony Lost Colonies]] where the colonists have degraded to the point where they don't know how to make anything new. One such world involves an unending war between the humans and the Insects, who have also degraded. Both sides are able to run primitive industry, such as making bullets, but it's mentioned that the helicopter that a character ends up crashing is one of the last working ones in their fleet and is from the original ship's stock.
* ''Literature/TheLostRegiment'' features the Tunnels of Light that occasionally bring humans from Earth to Valennia. They are, in fact, [[spoiler:teleporters placed on numerous planets of the ancient starfaring race that nuked itself back into the Stone Age. Their descendants are the Tugars, the Merki, the Bantag, the Kazar, and other hordes. In the second novel, the Merki go against their traditions and raid some of their ancestral burial grounds for Lost Technology, which they use to power their new airships. Due to the symptoms of the sickness that painfully kills anyone near the engines, they can be assumed to be nuclear in nature]].
* In the ''Literature/{{Darkover}}'' series, matrix technology is essentially MagicFromTechnology fueled by PsychicPowers. During what would later be called "The Ages of Chaos" things got a little out of hand and warfare routinely included summoning creatures from other dimensions and unleashing devastating energies. This eventually led to the [[FantasyGunControl Compact]], which banned ''all'' distance weapons. Over the centuries, the Darkovans developed a superstitious fear of returning to those troubled times, and consequently lost the knowledge of how build or safely use most matrix technology from that era. What was still around was studiously avoided by most people, causing society overall to regress to a largely Medieval level.
* In ''Literature/AwakeInTheNightLand'' millions of years pass during the course of the book, along with them some of the technology of previous eras is lost, mainly how to create some of the AppliedPhlebotinum. However sometimes the knowledge is regained through prophetic dreams.
* ''Literature/TheStormlightArchive'':
** Subverted. Modern scholars are obsessed with rediscovering ancient {{Magitek}} fabrials, marvelous machines that could do all sorts of things like heal and create things from thin air--not to mention the magnificent [[AbsurdlySharpBlade Shardblades]] and [[PoweredArmor Shardplate]], weapons and armor which can turn the tides of entire wars. But as Dalinar's visions show, the ancients didn't actually ''have'' any technology. They had the Blades and the Plate, but other than that they were actually of significantly lower tech level than the modern era, which confuses the people he confides in. This is because world-breaking [[ApocalypseHow Desolations]] would knock people back into the Stone Age every few centuries; it was so bad that the divine Heralds weren't even sure that civilization would have rediscovered ''bronze'' by the time they come back to help fight again. [[spoiler:The Shardblades were actually the [[BondCreature bonded spren]] of the Surgebinders, and thus were not technology at all, hence the apparent contradiction]].
** In ''Literature/{{Oathbringer}}'' (the third book), the heroes are in Urithiru, the long-lost ancient city of the Knights Radiant. They are shocked that there is barely any technology at all; there are fabrial elevators and plumbing, but those are just clever applications of technology that the modern world has already rendered obsolete. The ancient Knights Radiant, with their [[FunctionalMagic Surgebindings]], had very little need for any sort of technology.
* All three factions in the ''Amtrak Wars'' have lost technology. The Mutes are the mutant descendants of people stuck above ground during the nuclear war. So much has been lost by them that being given crudely-made crossbows is a big step up in technology for them. The other two factions the Iron Masters and the Amtrak Federation are far more advanced but both DELIBERATELY lost a particular technology. For the Iron Masters, they feel it was electricity that led to the nuclear war so they rid themselves of it while the Amtrak Federation forbid gunpowder technology for fear of their Mutes enemies capturing and reverse-engineering them. So the Amtrak Federation restricted themselves to air-powered firearms which are more difficult to reproduce and less powerful to use in case some guns are captured.
* In ''Literature/ThePillarsOfReality'', this has gradually happened. The technology possessed by the Mechanics is better when it's older (provided it has been maintained), because newer attempts to duplicate it tend to be inferior. Each succeeding generation has less and less understanding of it.
* Implied in ''Literature/TheDinosaurLords'' when Florian and Jaume find ruins of an ancient temple, with strange burn marks on the walls. They note that with technology they have, they couldn't produce temperature this high and make burns this small, and lightning doesn't tend to go in straight lines like the marks do. [[spoiler:The readers can, however, guesss it's been left by lasers, or something laser-like.]]
* ''Literature/TheCitizenSeries'': It's indicated that a lot of old Earth ("Third Civilization") knowledge has been lost, leading to a certain degree of SchizoTech between the Home Worlds, the colonies, and especially the Riders who have devolved back to Stone Age nomadic hunter-gatherers. Destry comes up with several innovations (for example, UsefulNotes/WorldWarII fighter plane doctrines applied to frame fighting) by going over surviving historical records.
* ''Literature/AConnecticutYankeeInKingArthursCourt'' is an unusual example of this Trope being invoked: as a side-effect of the Church decrying King Arthur's Court and deciding to decimate everything and everybody involved with it for their blasphemy; they destroy all of the technology and knowledge that "The Boss" (the titular Yankee, who has [[BringingRadioToTheRomans Brought Radio To The Romans]] and caused an industrial revolution several hundred years early) has made.
* In the period mystery ''Murder In The Place Of Anubis'', some unguent-stains on the victim's kilt are identified by King Tut's royal perfumer as a ''very'' rare type for which the recipe was lost decades ago. This is a telling clue, because [[spoiler: the victim and his murderer had conspired to rob a century-old tomb in which some of that unguent had been placed as grave goods.]]
* In ''Virtual Mode'' (and further in the ''Mode'' series), by Creator/PiersAnthony, Darius' dimension has a technology know as "chips" that permit Dimensional Travel: one setting allows a one-time link between the host dimension (the one with the activated chip) and a random destination, or a more permanent "virtual dimension" that requires five anchors that lasts until one of the anchors is released. This tech was '''deliberately''' lost (by being left in Darius' dimension), because as it turns out one of those dimensions had an empire that would use it to take over the multiverse....
* ''Literature/RoguesOfTheRepublic:'' The MagiTech the ancients left behind. For the most part, the modern countries have a good understanding of how it all works and can replicate much of it, but the greater wonders like levitation crystals and automated golems remain out of reach.


[[folder:Live Action TV]]
* In ''Series/BattlestarGalactica2003'' this is very much the case with Cylon technology, and indeed most technology in general. The [[AdvancedAncientHumans people of Kobol]] apparently invented things like organic Cylons and Resurrection in the distant past. Knowledge of this was lost in the conflicts that led to the settlement of the Twelve Colonies. The rediscovery of these technologies sparked a renewal of hostilities between the mechanical Cylons created in the Colonies and their human makers.
* ''Series/GameOfThrones'': Valyrian steel can be reworked by experts, but no one knows how to make it anymore.
* The premise behind the Franchise/StargateVerse; on two distinct levels no less. Present day back to the era of the first BigBad (Goa'uld), and their good counterparts (Tok'ra). And in later seasons from there to the [[SortingAlgorithmOfEvil even older Big Bad]] (Ori), and ''their'' [[{{Precursors}} good counterparts]] (Ancients). The "they were destroyed by their technology" part of this trope doesn't apply so much in this case, as the race which nearly all of the technology in question came from was wiped out by [[spoiler:a plague, and then another alien race destroyed the survivors before they could rebuild.]]
* In the ''Series/StarTrekVoyager'' episodes "Message In A Bottle" and "Hunters" the ship comes across a vast abandoned network of relay stations (over 100,000 years old; each powered by its own black hole!) enabling them to make contact with Starfleet on the other side of the galaxy.
* The eponymous ship in ''Series/{{Andromeda}}'' is a High Guard capital ship that survived the fall of the Systems Commonwealth and three centuries of the following intergalactic dark age orbiting a black hole at a distance where TimeDilation brought shipboard time to a standstill. Unusually for this trope the protagonists have access to it and the highly advanced antique tech onboard from the pilot on, being the salvage team that pulled it out and the sole surviving member of the original crew (plus [[SapientShip the ship herself]]).
* ''Series/LandOfTheLost'' was full of this. In fact the Land itself was a pocket universe created by Altrusian technology.
* Of the [[TheMultiverse many worlds]] encountered in ''{{Series/Spellbinder}},'' both the Land of the Dragon Lord and the Land of the Spellbinders were based on lost and irreplaceable technology. In fact, [[CoolOldGuy Regent Correon's]] biggest goal in the series (besides helping Paul get home) is finding a way to repair power suits and flying ships- or construct new ones. The Land of the Dragon Lord has TheEmpire protected not by a standing army but by a highly-advanced photonic computer. Naturally, no one alive has any idea how to fix it once Ashka rips out a key component. Another world had a primitive AfterTheEnd society telling stories of [[AIIsACrapshoot evil machines]] that destroyed their world. The protagonists end up unwittingly finding and fixing an AI-controlled APC. Oops.
* ''Series/{{Dinotopia}}'': The AdvancedAncientAcropolis of Poseidos has [[NinjaPirateZombieRobot robot dinosaurs]] powered by [[PowerCrystal Power Crystals]].
* ''{{Series/Fringe}}'' has introduced this with an ancient race who developed the technology to destroy an alternate universe. You might not think that would be a useful thing, unless you [[ContrivedCoincidence just happened to be]] in the middle of a war with an alternate universe.
* ''Series/BabylonFive'':
** A great war resulted in [[spoiler:Earth]] reverting back to roughly Middle Ages technology, centuries after the end of the eponymous space station. The occasional discoveries of that old time's technology is mostly due to [[spoiler:Rangers planting them to be "discovered" by the locals, in order to help them rebuild civilization on their own. One of the monks, who happens to be Ranger, gives a report to his superiors and asks them to provide the next Lost Technology in an ''old'' container unlike the last time]].
** There's also companies like IPX ('''I'''nter'''P'''lanetary '''E'''xpeditions), who travel to planets that were once home to long-dead civilizations, looking for Lost Technology among the rubble. While they have a tendency to find more than they bargained for (such as the Ikarran protector that started tearing through B5), they have also found useful things ([=EarthForce=] Interceptors, point defence guns so accurate they can reliably [[ShootTheBullet swat out of the sky enemy weapon fire]] and casually annihilate fighter attacks coupled with an energy barrier to soften what enemy fire gets through, were reverse-engineered from an ancient alien starship found by IPX).
** That's the entire plot of the ''Series/{{Crusade}}'' spin-off, where the crew of the ''[[CoolShip Excalibur]]'' is on a mission to look through old ruins on various worlds in an attempt to find a cure for the Drakh plague that will kill the population of Earth in 5 years. Had the show not been cancelled, they would have found a cure by the end of the second year and the plot would have radically shifted away from this.
* The source of the Rangers' powers in ''Series/ChourikiSentaiOhranger'' is technology created long ago on Pangaea that U.A.O.H. excavated.
* A small-scale case in Series/SeaQuestDSV; after the ten year {{Timeskip}} between seasons two and three, Captain Bridger [[LampshadeHanging actually asks]] Captain Hudson why they didn't build a new [=seaQuest=] to replace the missing one. Hudson explains that because the world has politically fractured apart during the crew's missing time, the technology that went into the ship is now controlled by the UEO's enemies, who have no interest in such a thing. The technology is thus still around but is lost to the UEO.
* Used in a downplayed fashion in the ''Series/DoctorWho'' serial "Paradise Towers", which is set in a massive tower block which has been isolated from the rest of the universe and degenerated into anarchy and savagery. The Doctor is at one point kidnapped by a gang of near-feral teenage girls, and one of the ways he gets them on his side is by showing them how to use a drink vending machine that's been in their lair all the time without them realising what it is or what it can do.

* In Music/{{Rush}}'s "2112", the TragicHero finds an electric guitar, just to be told by TheOmniscientCouncilOfVagueness that it's worthless and it caused the destruction of the elder race of man. [[spoiler: The hero can't take it anymore and commits suicide.]]

[[folder:Multiple Media]]
* In ''Toys/{{BIONICLE}}'', just about every bit of technology was considered lost on the desert planet of Bara Magna. Non-functioning battle machines were littered among the dunes, and the characters fought with depleted energy-weapons, using them as plain spears or swords. However, most of the characters ''did'' know what their function was and how they worked, having used the technology themselves during the Core War that devastated their planet -- they simply didn't have the resources or the knowhow to repair most.\\
Later it's revealed that their very settlements have actually been bits and pieces of an ancient exploded HumongousMecha, and that uncharted regions of their planet still contained a lot of unknown technology, none of which they had been aware of for a hundred millenia.

* In ''VideoGame/LoonyLabyrinth,'' the "Loony Machine" is a TimeMachine built by ancient {{Precursors}}.

[[folder:Tabletop Games]]
* Lost technology and the remnants of a star-spanning Galactic Republic are a central part of the setting of ''TabletopGame/FadingSuns'', where mankind has descended into a new feudal age and most technology is considered sinful or even blasphemous by the Church.
* First Age artifacts, especially warstriders, from ''TabletopGame/{{Exalted}}''. Subverted in that the technology isn't quite lost, just rare and only buildable in certain places or by certain people.
* The Brothers' War that underpins nearly all of the early storyline of ''TabletopGame/MagicTheGathering'' was begun when the two brothers found the Lost Technology of the Thran.
* The golden age of Humanity in ''TabletopGame/{{Warhammer 40000}}'' was brought to an end around the 25th millennium by the one-two punch of the "soulless" [[TurnedAgainstTheirMasters rebelling]] [[AIIsACrapshoot robots]] known as Men of Iron and the increased activity of the warp storms [[note]]Possibly caused by either Eldar creating [[EldritchLocation the Eye of Terror]] or increased population of psychically active races (mostly human). The Fall of Eldar shortly cleared warp storms, but they reappeared and the Astronomicon was established to maintain FTL travel.[[/note]] which shut down interstellar travel for several thousands years. As a result, the advanced Standard Template Constructs that contained its technological knowledge were damaged and/or destroyed, leaving humanity with but a fraction of their scientific and industrial knowledge. The current [[TheEmpire Imperium of Man]] rebuilt human technology by recovering knowledge from these artifacts of the ironically-nicknamed "Dark Age of Technology". (The Dark Age of Technology is also, confusingly, known as the Golden Age of Technology. Whilst human technology verged on CrystalSpiresAndTogas at times, it is considered a spiritual dark age by the Imperium.)
** There is also lots of other 'archeotech' out there from several of the other races, mostly the Slann/Necrontyr and the Old Ones/Eldar. It's heavily implied that three of the main races from the setting are forgotten and lost biological weapons.
** The Necrons are ancient skeleton machines scattered through the universe.
** The most spectacular pieces of Lost Technology are the Talismans of Vaul, aka Blackstone Fortresses. Giant, space-station-sized, quasi-sentient weapons capable of channeling pure Warp energy, and the only weapons capable of hurting the C'tan. Created by the pre-Fall Eldar, they were found abandoned by the Imperium in the Gothic Sector in early M33. The Imperium employed them, even though they were only able to use basic point defense and life support systems. [[spoiler: Abaddon launched 2 separate Black Crusades to find remote control devices for the Talismans and another one (12th) to capture them. The 12th Black Crusade, the Gothic War, culminated with Abbaddon using three of them, to anihilate a habitable star system, by turning its star into a supernova. As Imperium/Eldar reinforcements poured into the Gothic Sector, Abaddon used one fortress to lure the vanguard forces. During the boarding action, Abaddon set 4 Talismans to self-destruct to deny them to the Imperium, while retreating two remaining ones to the Eye of Terror. During the 13th Black Crusade, one Talisman was used to destroy a Hive World in the Cadian System, to lure in and kill Eldrad and in an failed assault on Cadian orbital defenses, while another one was allegedly destroyed by a Necron battlefleet. (most of it was retconned with relaunch of the 13th Black Crusade)]]
*** In general, as warfare escalates, Eldar pull more advanced and rare equipment from their vaults, up to superheavy walkers and grav tanks and Exterminatus grade [[WeaponOfMassDestruction Weapons Of Mass Destruction]]. They try to avoid using them because of their rarity and because large scale warfare tends to feed Chaos Gods.
** One of the Imperium's driving goals is to avert this trope by rediscovering the lost Standard Template Constructs. In one expanded universe novel, the elation the protagonists feel when they discover one gives way to horror when they realize that it produces [[spoiler:Men of Iron. Even worse, it's tainted by Chaos, which might explain why the original Iron Men rebelled in the first place.]] One of the characters in this instance relates the story of a group of scouts who found an STC which held the schematics for nothing more than a new kind of combat knife. Each of the scouts was given an entire ''planet'' for this discovery.
* ''TabletopGame/GammaWorld'' is a haven for Lost Technology.
* Anything more advanced than a lighter in ''TabletopGame/{{Rifts}}'' is either lost technology or reverse-enigeered from lost tech. The Glitter Boy is a shining example of both - not only do most of the suits in existence come from before the Cataclysm, but the only new ones come from Free Quebec, who managed to work out their mechanics. The exception being {{Magitek}}, the vast majority of which is imported from other worlds and/or dimensions; most notably the [[EldritchAbomination Splugorths]] via Atlantis. Or home-built by Techno-Mages, who are VERY prominent in the setting.
* ''TabletopGame/BattleTech'' has '[=LosTech=]' which is ExactlyWhatItSaysOnTheTin. Well it's technically old Star League tech that was never proliferated or was destroyed during the [[ForeverWar Succession Wars]], but don't go telling the Successor Houses that. The [[FasterThanLightTravel Kearny-Fuchida Drives]], extra-light fusion reactors, many types of weapons and armor, PowerArmor, [[InvisibilityCloak active camouflage]], and the black-box SubSpaceAnsible are just some of the many devices lost during the Succession Wars. The Clans managed to save quite of a lot of tech when they fled the Inner Sphere at the start of the Succession Wars. Three hundred years later, they return ([[GeneralFailure attempt]]) to crush the Successor States who are only starting to rebuild their infrastructure. As the series goes on, [[ApocalypseNot many technologies are rediscovered]].
* The Fringepaths created by the Tehrmelern race in ''Fringeworthy''.
* ''TableTopGame/EmpireOfThePetalThrone''. Some examples of the previous human civilization's technology exist, but they're considered magical by the current medieval level society.
* Third Edition ''TabletopGame/DungeonsAndDragons'' formally defined "lesser artifacts" as magical Lost Technology: items of great power that could no longer be manufactured by mortals. This distinguished such powerful, yet non-unique items (e.g. staff of power) from singular items like the Wand of Orcus. Many published D&D settings have complex historical backstories involving long-forgotten civilizations, the better to account for why so much Lost Technology can be found lying around in monster-infested holes in the ground.
* Judges Guild's campaign world (City State of the Invincible Overlord, City State of the World Emperor, etc.) is a standard fantasy setting with spells, magic items and medieval level technology. However, some supplements have examples of high tech relics from the past.
** ''Revised Guide to the City State'' (of the Invincible Overlord). The contents of the Hell-Bridge Temple treasury include two walkie-talkies, each charged for 10 uses.
** ''The Fantastic Wilderlands Beyonde''
*** Sea of Five Winds hex 0307. An audio system that can perform recording and PA (Public Address) functions.
*** Sea of Five Winds hex 1828. A usable periscope lies under a table in a partially burnt cottage.
*** Elephant Lands hex 4207 has a partially operational tape recorder.
*** Lenap Idyllic Isles hex 2107. A corroded battery can be found in a leather pouch.
*** Lenap Idyllic Isles hex 2410. A "dangerously operational" steam locomotive is in a crumbled temple.
*** Lenap Idyllic Isles hex 3432. An airplane propeller is used as a ship's anchor.
*** Lenap Idyllic Isles hex 4912. Beneath a tower are six deep-sea diving suits and twelve oxygen tanks.
** ''Wilderlands of High Fantasy'' (Issue N) had a plethora of relic high tech items with little description, including a parachute, hang glider, airplanes (prop-driven and jet), a helicopter, a re-entry capsule, a "spacecraft", an [[ReactionlessDrive anti-grav]] vehicle, a "fully operational flyer harness" (JetPack), an "underwater suit" (diving suit?) and mechanical PoweredArmor.
** ''Wilderlands of the Magic Realm''
*** Isle of the Blest hex 4131. In the broken hulk of a ship can be found a functioning optical rangefinder.
*** Isle of the Blest hex 4226. A defective crawler/tractor digging machine, deep within an ancient silver mine.
*** Before Island has a hidden laboratory complex that contains android parts and other mechanical devices.
*** Ebony Coast - Ruins and Relics. In hex 4523 a hill giant uses the stainless steel rudder of an ancient ship as a gardening tool.
*** Idyllic Isles of the Ebony Coast hex 4506. A high tech artifact powered by geothermal energy projects a laser {{hologram}} of an elven princess.
*** Ghinor Islands hex 3102. On the island of Skymetal Rock is a building framework made of steel girders.
*** Ghinor - Ruins and Relics. In hex 3406 is an underwater laboratory, the lair of a mad scientist looking for experimental subjects.
*** Ament Tundra - Ruins and Relics. A fully operational hang glider is tied down to a small hill in hex 4423.
** ''Wilderlands of the Fantastic Reaches''. Silver Skein Isles - Ruins and Relics. In hex 3530 is an ancient machine that travels in a two-mile diameter circle in the ocean. It is a 40 foot long, cigar-shaped object made of seamless metal (possibly a submarine).
* Averted in ''TabletopGame/MutantChronicles''. While the general tech level of the far future is equivalent to that of the 1950s (with some exceptions) this is not because technology is lost, but because electronic devices, especially those with integrated circuits, are an open door for the {{Eldritch Abomination}}s of the setting. Blueprints and drawings of pre-regression devices are carefully preserved and copied, and the theory behind them is well understood. As soon as humanity finds a way to keep the BigBad out, restoring everything from home computers to {{Kill Sat}}s will take take no more than a few months.
* Since the Broken Lands of ''Remnants'' are still recovering from the last apocalypse, all technology is lost and functional stuff is more precious than anything else. The most likely to be functional, due to advanced self-repair? Mecha.
* HoylesRulesOfDragonPoker claims special Dragon Poker decks existed once, but none have ever been found. Of course, there's a penalty for not playing with a Dragon Poker deck.
* More technology exists in ''TabletopGame/RocketAge'''s past than its present. Mars was once a technological paradise, the Erisians had some very developed medical and military technology and Io is also implied to have been very advanced before the Europans decided their neighbours' cities would look better as craters. In fact, most new Earthling technology is inferior reverse engineered Ancient Martian technology, with the possible exception of the rocket ship and some of Tesla's inventions.
* ''TabletopGame/{{Numenera}}'': The titular devices are the remnants of ''various'' examples of the "AndManGrewProud" version of TheEndOfTheWorldAsWeKnowIt (eight times over, the game setting being the "Ninth" World) that have some amount of RagnarokProofing... and even then, the majority of them only have one use left in them before they short out forever.

* The basic premise behind ''Theatre/WeWillRockYou'', where music itself is the Lost Technology.

[[folder:Urban legend]]
* According to legend, vitrum flexile, or flexible glass, was supposedly invented in the 1st century AD by a Greek whose name has been lost to time. He demonstrated to Emperor Tiberius Caesar that it wouldn't break, only be dented, and could easily be restored with a small hammer. [[HaveYouToldAnyoneElse Tiberius asked if the inventor had told the secret of the flexible glass to anyone else.]] When the inventor confirmed that he was the only one who knew, Tiberius had him executed. He didn't want the flexible glass to devalue gold and silver.

[[folder:Video Games]]
* A twist on this is ''VideoGame/{{Fallout}}'', which takes place in a post-apocalyptic USA, beginning 84 years after a massive nuclear exchange that took place in the year 2077. The local BigBad has recovered terrifying Lost Technology -- in the form of a powerful nuclear weapon from the beforetime!
** Played with [[VideoGame/Fallout4 The Institute]]: They've advanced their technology past the Pre-War age, but they LACK in so many areas (social, most of all) that they're starving themselves in certain areas and don't realize it. This leads to barbarism and organized crime with robot slaves. Your best option is to MAKE their technology Lost so that they'll be forced to take jobs with real organizations of the Fallout era.
** The Brotherhood of Steel are all about enforcing a ban on this trope, collecting and warehousing (though some might call this 'hoarding' instead) dangerous pre-war tech, and use the more low-key versions of it (such as energy weapons and PoweredArmor) to enforce this ban. [[MotiveDecay Or, at least, they used to,]] but between several ideological schisms, branch groups going AWOL and a massive war on the West coast, they have alternatively forgotten their creed or [[KnightTemplar went completely overboard with it]]. In ''New Vegas'' especially, they begin discovering that, like it or not, the world is going to rediscover and use this lost technology and leave their dwindling order behind.
* Central to the ''Franchise/{{Halo}}'' series:
** The entirety of [[VideoGame/HaloCombatEvolved the first game]] is set on the titular [[{{Precursors}} Forerunner]] ringworld, which also happens to be one of seven identical superweapons designed to kill all life in the Milky Way. The 100,000+ year-old installation also comes with a whole set of self-replicating robotic guardians. We later find out there are six more of these.
** In ''VideoGame/{{Halo 3}}'', we get the Ark, [[spoiler:a ''massive'' structure (about 100,000 km across) sitting outside the Milky Way that serves as a control room for the Halos.]]
** ''Literature/HaloGhostsOfOnyx'' gives us a Forerunner Shield World, which is basically a DysonSphere designed to protect against the effects of the Halos; the one in ''Onyx'' is bigger inside than it is outside. And in ''VideoGame/HaloWars'', we end up inside [[spoiler:a another Shield World, this time with a whole fleet of [[CoolStarship Cool Starships]] hidden inside.]]
** Off-screen, Forerunner technology was what fueled the creation and technological advantage of the Covenant; it was founded by a group of Prophets who took to the stars in a Forerunner Dreadnought and decided to keep looking for more "sacred" Forerunner relics, which they reverse-engineer to produce the majority of Covenant technology. In fact, the entire war against the Hunters started simply because some of them were eating the stuff.
** ''VideoGame/{{Halo 4}}'' takes place in a Shield World called Requiem, which consists of multiple, artificial layers ensconced on-top of each other, with the outer-most layer designed to make it impenetrable to any form of offensive or breaching action - including the effects of the Halo Array. Requiem also contains more extant Forerunner technology, including a class of combat {{mecha}} (the Promethean Knights), a large selection of [[{{EnergyWeapon}} Forerunner-manufactured weaponry]], and a [[spoiler:[[{{SealedEvilinaCan}} living, breathing Forerunner complete with a top-level combat skin]].]] ''4'' also introduces an {{Artifact of Doom}} from the ExpandedUniverse, the Composer, designed to [[spoiler:digitize any sentient organic within its effective range.]]
** ''Literature/TheForerunnerSaga'' - a trilogy of prequel novels detailing the last days of the Forerunner civilization - mentions the Organon, the most sought-after [[RecursivePrecursors Precursor]] artifact in all of Forerunner archeology. The final novel, ''Literature/HaloSilentium'', reveals that it's [[spoiler:actually the Domain, a vast, sentient, galaxy-spanning information network older than the current universe itself that the Forerunners were using to store the entirety of their history, precepts, and achievements.]] Unfortunately, it was lost forever when [[spoiler: the [=IsoDidact=] activated the Halo Array.]] Apart from the Precursor relics scattered throughout the Milky Way, the trilogy also reveals that some extant Forerunner relics were so old and advanced that the Forerunners themselves had forgotten how to build them.
** ''VideoGame/Halo5Guardians'' introduces, well, the Guardians, enormous bird-like constructs who enforced the Forerunners' rule over subject species; a single one is capable of policing an entire solar system.
* Nearly every early ''Franchise/FinalFantasy'' game has some elements (6 and 7 as Lost Magic), usually just to give you a chance to dungeon crawl through a high-tech tower of some sort. No one ever thinks to pick up a dropped laser gun or study the tech for the betterment of the world, though.
** The semi sequel/prequel ''VideoGame/DissidiaFinalFantasy'' goes into detail about the backstory of some of the lost technologies from ''VideoGame/FinalFantasyI'', which were only briefly touched upon in the original game.
** In ''VideoGame/FinalFantasyX'', the use of lost tech, or Machina, is forbidden (with some specific exceptions) by the [[TheTheocracy Church of Yevon]] due to it being the cause of human sin that is embodied in the giant whale monster Sin. There is a tribe of near humans, the Al Bhed, that ignore these teachings and are thus widely shunned.
* A major element in ''VideoGame/WildARMs1'' and ''VideoGame/WildARMs3''. In fact, [[spoiler:in the first game, the protagonist Rudy is ''made'' of lost technology, and one that nearly destroyed the world to boot.]]
* ''VideoGame/{{Xenogears}}'':
** The game tends to flip-flop on whether Gears are or aren't lost technology. At the very least, Gears are dug up from ancient ruins, but it's painfully obvious that they can be tweaked and created via available tech in the more advanced areas. At the very least, the Omnigears are lost tech.
** The remains of the Elridge, however, and the Zeboim civilization, very much fit the trope. The Merkaba, the "Treasure of Kislev," the Yggdrasils, and Emeralda herself are primary examples.
** Carried through to its spiritual prequel ''VideoGame/{{Xenosaga}}'', archeologists digging up the Zohar and building the Zohar Emulators, a technological bridge to higher planes of existence that is responsible for the historical divine miracles and a theoretically infinite source of energy. In true lost tech style these higher planes also contain the Wave Form Existence/God/Chaos/U-DO, the big bad of the series.
* ''VideoGame/SecretOfMana'' centers around the attempts of the BigBad to acquire the ancient world-destroying Mana Fortress and Mana Beast.
* In ''VideoGame/BrainLord'', you fight through many gimmicky Lost Technology dungeons.
* ''VideoGame/ChronoTrigger'' has different technology available in different eras. As the game is based on TimeTravel, however, if something is Lost Technology in the modern era, you can go to the era where it was developed and where it's not "lost." [[note]]This particular timeline is only true for Chrono Trigger. Due to temporal meddling, VideoGame/ChronoCross has more examples, and some technology that's lost in Trigger is unlost there.[[/note]]
** The Enlightened Ones of Zeal in 12,000 BC use {{Magitek}} that no era, not even the future, can match. However, when [[AndManGrewProud Man Grew Proud]] and Zeal fell from the skies, the knowledge of Zeal was lost. Though relics from the Dark Ages survive, such as the Masamune, the Sun Stone and the Pendant of the Guardia royal family, the power of magic was lost to humans, {{Magitek}} was never rediscovered, and technology in the future went down a purely nonmagical path.
** In one specific case, the red mineral called Dreamstone was commonly used to make powerful technological and magical devices during the Dark Ages, but all sources of it have dried up by the modern era. This becomes a problem because, while Melchior has the technological and magical knowledge to reforge the [[SwordOfPlotAdvancement Masamune]], he doesn't have any Dreamstone to use in the alloy, necessitating a FetchQuest in 65,000,000 BC.
** Prior to TheEndOfTheWorldAsWeKnowIt in 1999, human technology had advanced to levels roughly equal to the Enlightened Ones, but all of that ended on the Day of Lavos. In 2300, humans are no longer developing new technology, and humanity only [[ScavengerWorld clings to existence by maintaining 300-year-old relic machinery]]. [[spoiler: There ''is'' a facility that's building new machinery, but the robotic Mother Brain who rules Geno Dome is completely hostile to humans.]]
** 65,000,000 BC is an odd situation. The Neanderthals are Stone Age hunter-gatherers, but their craftsmanship is good enough to develop weapons superior to anything available in the modern world, including guns and robotic arms. Though this is partly GameplayAndStorySegregation (especially the Stone Arm), at least part of it is implied to be through the use of Dreamstone, which the Ioka Tribe knows about but, as humanity has not yet evolved magical abilities, cannot utilize to its full potential. No weapons from 65,000,000 BC are known to have survived in any other era, but you can take them to the future yourself if you choose. Also, Elixir is freely available to the Ioka (and called Sweet Water), but after the coming of Lavos, the Sweet Water stops flowing and Elixir becomes a fairly rare item afterwards.
* ''Franchise/MassEffect'':
** A large part of the story of the original trilogy revolves around the galaxy's dependence on AppliedPhlebotinum that were created by the Protheans, a mysterious race that died out 50,000 years ago. However, [[spoiler:it is later revealed that the Phlebotinum were in fact Lost Technology to the Protheans as well; they were created nearly 1 billion years ago by either the Reapers, a race of [[DeusEstMachina Mechanical]] {{Eldritch Abomination}}s or their own {{Precursors}}, the Leviathans, a race of [[EldritchAbomination Aquatic Horrors]], and that these artifacts were specifically intended to be found by later civilizations in order to guide their technological development along a specific path.]]
** ''VideoGame/MassEffectAndromeda'' has everyone in the Heleus Cluster of the Andromeda galaxy fighting over super-technology known as the Remnant, which also fights back itself since its automated caretaker robots don't view people coming to reverse engineer things very kindly. Played with a bit in that the Remnant scans as only being around 300 to 400 years old, a lot newer than most LostTechnology. [[spoiler:The Remnant is ultimately revealed to be a vast terraforming network left behind by a civilization known as the Jaardan, who abandoned it and went elsewhere when the Scourge was unleashed on Heleus. What the Jaardan intended to do with Heleus once the terraforming was finished remains unknown, as does the reason why some unknown enemy used the Scourge on them.]]
* Creator/BioWare also invoked this Trope with ''VideoGame/KnightsOfTheOldRepublic''. The Rakata technology and Star Maps were an unholy cross of well-built, heavily-guarded technology infused with the DarkSide of TheForce. A virulent plague, slave revolts, [[AlwaysChaoticEvil warring amongst themselves]], and a mutation rendering the species Force-deaf sent the planet back to the stone age. By the era of Darth Bane, the species is extinct, meaning any hope of recovering the tech is lost forever. And as detailed in other ExpandedUniverse works, the Force-powered hyperdrive used by the Rakatans was reverse-engineered by Correllians. Every hyperdrive built since then is based on the resulting designs, and even thousands of years later nobody completely understands the underlying principles of hyperspace.
* ''Franchise/{{Metroid}}'': The Chozo had marvelous technology, widespread over many a planet the player visits in a game, all of which Samus inevitably collects, blows up or uses during the plot to refill her BagOfSpilling. Same with their oneshot intergalactic Pen-Pals, the Luminoth. One only has to take a look at one of the few remaining Chozo weapons that is still seeing active service, namely Samus' iconic PoweredArmor, to realize that the Chozo were incredibly powerful.
* The Xbox remake of ''VideoGame/NinjaGaiden'' features a statue with floating stones. This power, it is said, "clearly shows that it was not made with modern technology" and "must be the product of an ancient age". [[ChekhovsGun It becomes important later]].
* The RPG ''VideoGame/DokaponKingdom'' actually has an item CALLED "Lost Technology." It unlocks a new character class, the Robo-Knight--male characters who use it become {{sentai}}-style mechs, while female characters become {{Robot Girl}}s.
* ''VideoGame/MegaManLegends'' is all over this trope. From the [[ScavengerWorld setting]] to the [[SealedEvilInACan plot]] to the [[DramaBombFinale Big Reveal]] at the end of the sequel to the ''[[GlobalCurrency world's money]]'', it all has to do with Lost Technology.
* ''VideoGame/MightAndMagic''. [[spoiler:In the case of the first five games, possibly deliberately lost, to keep people from messing up with the experiment that is the reason why their worlds' names are written in all Capital Letters. From a certain point of view, the BigBad is ''himself'' a piece of malfunctioning Lost Technology. Might & Magic 6, 7 and 8? TheEndOfTheWorldAsWeKnowIt resulted in a collapse of civilization bringing them down from energy-weapons to just being up to cannons a thousand years later, but some pieces of what was before are still around...]]
* Av Kamiw in ''VideoGame/{{Utawarerumono}}''. Basically, giant Evangelionesque mechas in a world where very few people like herbalists know of gunpowder, and fear it too much to use it. GameBreaker much? (They still go down to swords and arrows then it's the protagonists attacking, of course.) The last stage of the game is also set in an abandoned research laboratory that has a few crumbling remnants of working technology, but it's generally useless stuff like holograms that tell us about the backstory.
* ''VideoGame/NeverwinterNights'' gives us the incredible magic of the Old Ones (lizard-people precursors) (who used it to create a stasis shelter to protect them from global cooling) and the powers used by the people of Netheril to levitate their cities. In the Netheril case, it ultimately came from the [[ForgottenRealms mother setting]], with an interesting explanation for ''why'' the ability to shear the tops of mountains and levitate them were lost: the old method to do so became impossible to use when the rules of magic were re-written.
* ''VideoGame/NeverwinterNights2'' gives us the Illefarn BigBad, created with Lost Technology, and their Song Portals (which can be duplicated at greater expense by modern magic.)
* The ''VideoGame/JakAndDaxter'' games feature the shiny orange artifacts, structures, and machinery of the Precursors.
* ''VideoGame/TalesSeries'':
** Played with in ''VideoGame/TalesOfSymphonia'' and ''VideoGame/TalesOfPhantasia'', where magitechnology ''was'' lost, but is just being rediscovered. In both cases, as well as during the 4000 years inbetween, one of the first pieces of technology to be reconstructed and rebuilt by archaeologist/scientists is the Mana Cannon, the superweapon the use of which destroyed the ancient civilizations that invented (and reinvented, and re-reinvented) magitechnology in the first place.
** Played with further in ''VideoGame/TalesOfVesperia'', which revolves around "Blastia": Lost Technology that is well-researched, widely-used and vital to modern life in the world. Even though the knowledge on how to create blastia has been lost, research has advanced to the point where basic preliminary models can be created. In another subversion of the usual formula, the solution to the heroes' problems is ''not'' using them.
* In ''VideoGame/TearsToTiara2'', the floating city of Tartetos has a bunch from the {{Precursors}} and earlier human times, including floating farms, buildings, and the ''floating city walls''. [[CorruptChurch The Holy Church]] is also actively suppressing knowledge, and many characters mention human technology that has recently been lost.
* The earlier ''VideoGame/ShiningForce'' games features a cast of traditional fantasy warriors, magicians, and creatures battling traditional fantasy evils. Except for the occasional sentient robot that survived through time to help the heroes.
* In ''VideoGame/PhantasyStarIV'', society has reverted to simpler, medievalish technology after [[spoiler: the protagonists of ''Phantasy Star II'' destroy Mother Brain, a supercomputer that controls all technology]]. Unfortunately, without her guidance, the technology controlling the planetary systems like climate, tectonics, and defenses, goes haywire and makes life tough for the survivors. At least until the heroes beat the BigBad and [[spoiler: let benevolent androids resume control of the systems.]]
* ''Franchise/TheElderScrolls''
** The now-extinct [[OurDwarvesAreDifferent Dwemer (Deep Elves or "Dwarves")]], were the most technologically advanced race known to have ever walked Tamriel. Blending SteamPunk machinery with [[{{Magitek}} masterful enchantments]] along with [[LoopholeAbuse bending the "Earthbones"]] (essentially the laws of physics and nature) allowed them to create technology far more advanced that any other race on Tamriel has come close to and has allowed their creations to [[RagnarokProofing last in working order for the thousands of years]] since [[RiddleForTheAges their disappearance]]. They are essentially a fantasy version of SufficientlyAdvancedAliens, leaving behind working lost technology such as {{Weather Control Machine}}s, HumongousMecha, and even a machine capable of safely reading [[TomeOfEldritchLore Elder Scrolls]].
** Likewise, the [[OurElvesAreDifferent Ayleids (Wild Elves)]] created many useful magical items during the golden years of their Empire, none of which have been replicated by the time of the games, forcing players to search Ayleid ruins in order to get their hands on them. Their magic items included Welkynd Stones and Wells which restore lost magicka, as well as Varla stones which can restore enchantments to weapons. The catch? The stones disappear after being used, and the wells need time to recharge. (According to some theories, the Ayleids themselves didn't "create" these items, but preserved them from the "[[TheTimeOfMyths Dawn Era]] magicks of the [[{{Precursors}} Ehlnofey]]", meaning they were a form of lost technology even to the Ayleids.)
* ''VideoGame/WorldOfWarcraft'':
** The main premise of the Uldaman and Ulduar dungeons, and the Uldum complex, though the technology itself does not come up much.
** Gnomeregan is a relative case, in that the advanced technology was only recently lost. The gnomes of WoW are the most technologicaly advanced people on Azeroth (all the way up to friging ''nuclear bombs'') but they lost their city to a trogg invasion during the third war (some seven years ago at the moment) and with it the best of their tech. It is a lowbie dungeon now, was and one of the most run for all the engineering drops. They rely on slightly less advanced SteamPunk style tech now (but they still have shrink rays and rocket launchers), but spend their time trying to (fruitlessly) retake their home.
* ''Franchise/AssassinsCreed'':
** ''VideoGame/AssassinsCreedII'' has [[spoiler: the Pieces of Eden being Lost Technology from a race that preceded humanity as the dominant species, appropriately called the Ones Who Came Before. They're true purpose is as of yet unknown but it may be part of a defense system to protect Earth from a solar flare. It should also be noted that according to Subject 16, they have many varied and versatile uses, since Tesla was planning on making free energy and a free global with the Fourth Apple, while Hitler used it to start WWII.]]
** ''VideoGame/AssassinsCreedIII'' reveals that [[spoiler:the Pieces of Eden turned out (unexpectedly even to their creators) to have ClapYourHandsIfYouBelieve properties. If enough people desperately wanted something while being the focus of a Piece, it would happen]].
* The fifth game in the ''ThunderForce'' series is about the discovery of a wrecked ship that humanity calls "Vasteel" ("Vastian's Steel" for short) and builds a line of technology based off it, including a supercomputer...which goes berserk.
* Discussed in a tavern conversation in ''VideoGame/InfiniteSpace''. A character notes that [[CultColony Adis]]' advanced technology is very close to the technology their precursors from Terra used to have, which leads another character to say the idea of their precursors had more advanced technology than the current generation is ridiculous. There are real examples, however, such as the Epitaphs, Void Gates and Cosmic Trade Authority.
* Various artifacts from the Sindar civilization in ''VideoGame/{{Suikoden}}'' series.
* The artifacts of the Xel'Naga in the ''VideoGame/{{Starcraft}}'' series. Even Protoss technology pales in comparison.
* ''VideoGame/StarcraftIILegacyOfTheVoid'' introduces the Spear of Adun, a [[TheMothership gigantic spaceship]] capable of carrying an entire civilization. Built during the Golden Age of the Protoss Empire, its technology is far beyond the ones they possess in the present day.
* Retrieving their Lost Technology is one of the major reasons the Dwarves continue to launch expeditions into the Darkspawn infested Deep Roads in ''VideoGame/DragonAgeOrigins''. Some of the lost thaigs still hold valuable secrets that could help turn the tide against the Darkspawn. Others have secrets that are better off buried and forgotten.
* While ''Franchise/TheLegendOfZelda'' series has plenty of examples of SchizoTech, actual Lost Technology has only appeared much later during the seventh generation and onward:
** A few centuries prior to ''VideoGame/TheLegendOfZeldaSkywardSword'', there was a thriving civilization made up mostly of sapient robots (and, probably, a related civilization that made the robots), with antigravity technology, mastery of electricity, and other technology to put modern Earth to shame. The civilization vanished around the time of a war against the BiggerBad, and ancient ridiculously high-tech relics show up in dungeons and as monsters for the rest of the series, a span covering literally thousands of years.
** Thousands of years before the events of ''[[TheLegendOfZeldaBreathOfTheWild Breath of the Wild]]'', the Sheikah created countless {{Magitek}} tools and machines to serve the people of Hyrule. [[spoiler:10,000 years before the start of the game, this technology was even used to help the princess and hero of that era defeat Calamity Ganon. However, one of Hyrule's kings feared the technological power of the Sheikah, and banished them from the realm; in response, the still-loyal Sheikah abandoned their technology.]] Nowadays, though even the Sheikah themselves have mostly forgotten the workings of their ancient creations, remnants of their technology can still be found around Hyrule. The very first item Link receives (after awakening from a high-tech-looking [[spoiler: resurrection chamber]], no less) is the Sheikah Slate, a tablet computer with maps, world-manipulating apps (runes, as the game calls them), NFC, and a camera that not only has a zoom function, but also an enemy scanner. Roaming around the world are powerful StarfishRobots known as Guardians, which attack with a laser seemingly unavoidable without cover or speed. And scattered around the world are over a hundred Sheikah shrines, some containing places to download (distill, as the game calls it) apps, and others containing miniature Guardians that are no less fearsome than their overworld counterparts. Also, there are towers throughout the world where Link can download new maps to his tablet, and the tablet's aforementioned NFC capability is used to unlock shrines, towers, and some treasure chests. Additionally, the four main dungeons are actually [[spoiler:ancient Sheikah AnimalMecha known as "Divine Beasts"]]. And, a more amusing example, there's an armor set that grants resistance to electricity due to being made of an exotic material whose creation method has been lost to time: [[spoiler:rubber]].
* ''VideoGame/SwordOfTheStars'' is rife with {{Precursor}}-tech, unfortunately most of it is shooting at you in the form of random encounters. The Morrigi in particular were once much more advanced than they are now and most of their "research" is simply re-discovering what they're lost.
* One form of treasure in the post-apocalyptic {{roguelike}} ''VideoGame/CavesOfQud''.
* In the backstory of ''VideoGame/DarkSouls'' the Witch of Izalith and her Daughters of Chaos were originally wielders of flame sorcery. The Witch's disastrous attempt to recreate the First Flame with her Lord Soul mutated her and most of her Daughters (only Quelana escaped unscathed). The original flame sorcery was lost and replaced by Pyromancy. The only traces of the original sorcery are the Demon Catalyst wielded by the Demon Firesage (the last practitioner of the flame sorcery whom you eventually kill) and the Izalith Catalyst that belonged to one of the Daughters of Chaos prior to the birth of Pyromancy.
* ''[[VideoGame/ExaPico Ar tonelico]]'' is absolutely swarming with semi-lost technology. There are a number of survivors from when the towers were originally built, but nearly everyone else can at most operate the doors and Reyvetail Cosmosphere connections. Controlling [[MechaMooks Tower Guardians]] is right out.
* In the world of ''Videogame/{{Arcanum}}'', magical and technological civilisations cycle, so, naturally, this occurs a lot. While the current society is basically a fantasy world undergoing industrial revolution, achievements of the previous hi-tech civilization include steam robots, a mild SuperSerum, a device that can resurrect dead (craftable of VendorTrash, no less), a pistol [[PunchPackingPistol that packs more punch]] than the game's resident {{BFG}} and another one that shoots ''plasma'', and [[spoiler: a device that can permanently kill a mage of tremendous power, which indirectly led to said civilisation's demise at hands of one such mage as a preemptive strike]].
* In ''VideoGame/SidMeiersAlphaCentauri'' and its expansion ''Alien Crossfire'', Planet itself is one massive piece of Lost Technology. Known to the alien Progenitors as Manifold 6, it was part of a grant experiment to create sentient planets. The other 5 ended up [[GoneHorriblyWrong going badly]] and wiped out the ancient Progenitor race, with their descendants working to rediscover lost tech. The two alien factions in the expansion, the Manifold Usurpers (who want to finish the experiment and [[AscendToAHigherPlaneOfExistence ascend]]) and the Manifold Caretakers (who want to prevent another catastrophe) also bring with themselves Ogre-class {{Spider Tank}}s that are bits of left-over tech from their ancestors. They can't build new ones or even fix the ones they have. When their advanced scouts crash-land on Planet, they spent the following years on equal footing with humans, working to rediscover even their normal tech in order to build a SubspaceAnsible and summon the fleet.
* Very possible in ''VideoGame/DwarfFortress''. As players build various devices over the course of days or even weeks, putting down connections and levers without labelling them, that thing is going to be inherited by a player down the line who will have absolutely no clue how to activate the device and no idea what lever does what. Since ''Dwarf Fortress'' players have a tendency to be [[VideoGameCrueltyPotential pointlessly sadistic jerks]] with a habit of building {{Pointless Doomsday Device}}s, and tantruming dwarves have a habit of throwing random levers without being told to, many fortresses meet an untimely end that involves a lot of magma getting into places where magma shouldn't be.
* Present but downplayed in ''Videogame/{{Tribes}}'', set after the ''Videogame/{{Starsiege}}'' series. ''Starsiege'''s signature HumongousMecha, the [=HERCULANs=], were briefly used in the Outlands in ''Tribes'', but replacement parts and the know-how on how to repair the very complicated machines meant that they were soon mothballed. The Tribes now use derivative HERC technology in their PoweredArmor, which are simpler, cheaper, easier to repair and far, [[JumpJetPack far more mobile]]. The Tribes do not seem to have lost any other knowledge, as they still produce advanced starships and energy weapons.
* ''VideoGame/HomeworldDesertsOfKharak'' involves a search for the Primary Anomaly in the middle of a great desert, a site where a satellite has detected metal similar in composition to the debris orbiting Kharak and a power source, whose level rivals Kharak's sun. By that point, the Kharakian people have known for a while that they're not native to this world, but they have forgotten that they have originally come to this world as exiles, forbidden to ever leave again.
* Carefully {{defied|trope}} at the end of ''VideoGame/KingdomOfLoathing'''s "[[ZombieApocalypse Zombie Slayer]]" challenge path. Your character remembers [[CallBack from the Grey Plague world-event]] that the zombie cure is synthesized from an infectee's pineal gland, and tells this to the Cola War medics in the past to SetRightWhatOnceWentWrong.
-->"Incredible!" The doctor rolls up his sleeves and reaches for a scalpel. "I'll begin straight away!"\\
You put a hand on his shoulder. "One more thing, and this is the most important part. Once you've worked out the formulation of the cure, you must ''write it down''. Don't forget!"
* ''VideoGame/HorizonZeroDawn'':
** The opening sequence of the game presents robotic animals as just another facet of nature, and everyone, including the tech-phobic Nora, uses parts scavenged from these machines for making clothing, tools, armor, and weapons. Furthermore, the Nora worship something [[spoiler: namely, a giant mechanical door,]] which they call the All-Mother.
** A major plot point in the game is the Focus, a rare piece of lost technology that Aloy (the protagonist) finds early in the game and uses to interact with other pieces of lost tech. This [[spoiler:combined with the fact that she's the genetic clone of a scientist who had top-priority access to practically everything in the pre-apocolypse, in a world where genetic scanners had replaced locks and keys,]] and her extraordinary intelligence and tech-savvy gives her the means to access tech that few others can even dream of.
* The Holy Ryuvian Empire from the ''VisualNovel/{{Sunrider}}'' series possessed all kinds of advanced technology in its heyday, from AI-controlled capital ships to HumongousMecha to matter replicators to time machines. The empire has long since crumbled and much of its technology has been lost (it is explicitly called “Lost Technology” in-universe), but samples of it can be found on worlds throughout the galaxy. Several sidequests pit the player against automated Ryuvian mechs and ships that have come online after millennia of dormancy, and they prove to be some of the toughest enemies in the game.
** [[LivingRelic Sola vi Ryuvia]]’s personal mech, the Seraphim, is a scout model that has gone two thousand years without maintenance. Despite this neglect, its sniper rifle is powerful enough to punch holes through modern capital ships.
** The final boss of ''Sunrider Liberation Day'' is the Nightmare Ascendant, a fully intact and restored Ryuvian mech piloted by the series’ BigBad. This machine is so powerful that it can NoSell a direct hit from the Sunrider’s [[WaveMotionGun Vanguard Cannon]] and decimate an entire fleet singlehandedly. It ends up taking the combined firepower of a joint Alliance-PACT fleet, plus another shot of the Vanguard Cannon, to finally destroy it.
* In ''{{VideoGame/Foxhole}}'', the weapons and equipment resemble that of the World Wars period, but it actually takes place in an AlternateHistory future, after something like a century of constant warfare between the Colonials and the Wardens. This on-going war has cost them some of their technological advancements which is why the war resembles the familiar past. Their tanks in particular are both outdated and a rare sight on the battlefield.
* ''VideoGame/FateExtra'': Taken UpToEleven with the Moon Cell, a supercomputer on the Moon. Not a supercomputer built into the Moon, mind you, but the ''entire Moon itself'' is one enormous supercomputer. Carbon dating indicates that the Moon Cell pre-dates even the formation of the Earth, and its data manipulation abilities are so tremendous it qualifies as [[RealityWarper Reality Warping]]. Who built the Moon Cell is a total mystery, and there's only a scant amount of information on why they built it, as it seems to be passively observing everything that has ever happened on Earth. The games' plotlines often focus on people trying to control portions of the Moon Cell's power for their own benefit.


[[folder:Web Comics]]
* Most of the "ice gifts" in the ''Webcomic/GiftsOfWanderingIce''.
* The [[DinosaursAreDragons dragons']] [[PhlebotinumKilledTheDinosaurs Iridium Bomb]] in the second story arc of ''Webcomic/TheInexplicableAdventuresOfBob.''
* ''Webcomic/WapsiSquare'' has the golem girls as well as the calender machine. The former were responsible for destroying the civilization that created them, while the latter [[spoiler:trapped the world in a GroundhogDayLoop 1450 years long through 56 iterations until it was destroyed.]]
* The town of Crestfallen in ''Webcomic/SerenityRose'' is stated to be absolutely full of conjurations and sorcery that modern witches are totally incapable of replicating. Due to the mechanics of magic in this setting, this applies not only to the complexity of the things there, but to the fact that they are still around in the first place.
* ''Webcomic/SchlockMercenary'': The company discovers a cache of technology from a lost era of galactic history, along with the inheritors of that cache, who are happy to hire the company as thanks for reviving them. They quickly find that they have difficulty selling any of this technology, because all their potential customers know that "technology from a lost era" is a blatant con.
* A big part of ''Webcomic/{{Pacificators}}'' is that the world has been plunged into a second Dark Age and as a result, much of modern technology has been lost. The descendants of the survivors are trying to re-discover those old technology via archaeology. [[spoiler:Too bad there's some people who wants those technology destroyed.]]

[[folder:Web Original]]
* In ''Roleplay/TheGamersAlliance'', the [[TheMagocracy Alentian]] and [[ProudScholarRaceGuy Lefeinish]] devices are millennia old, dating back to the First Age, and are more advanced than anything developed in the Third Age.
* In ''Literature/FineStructure'', one of the protagonists [[spoiler:sends human civilization back to the stone age every time they get close to re-developing nuclear weapons. Nukes are Lost Technology and she intends to ''keep'' it that way.]]
* Literature/LandGames: [[spoiler:Farseer discovers his people once had weapons like those of the human players.]]
* ''WebOriginal/OrionsArm'' has its own name for such devices. [[http://www.orionsarm.com/eg-article/4b0d5fc969b5f "Clarketech"]] (derived from Main/ClarkesThirdLaw) is any piece of technology created or left behind by a highly advanced intelligence or alien civilization, which a member of a lesser-advanced civilization may be able to use but not understand or replicate. Devices like these are highly valued, and are eagerly sought after by treasure hunters known as "Clarkers."

[[folder:Western Animation]]
* In the ''WesternAnimation/{{Futurama}}'' episode ''Mother's Day'', Fry reinvents the wheel (which he shapes like an oval) after the robots rebel. This is however only a gag, as wheels are commonly seen in the show (particularly on robots).
** In a later episode, the crew go to a museum to find and use a thousand year old weapon... The heat-seeker missile.
** It's also been suggested that, at some point during the time that Fry was cryogenically frozen (possibly during the 24th Century), the world had experienced another Dark Ages. Yet, somehow, Fry remains cryogenically frozen during that time.
* Many of the Arkadian devices in ''WesternAnimation/SpartakusAndTheSunBeneathTheSea'' could count as Lost Technology; their creators died long ago and nobody today knows how to fix them - which is Very Bad because their artificial sun is dying.
* [[LivingRelic Xyber 9]], the Garden of the Ancients, battle medallions/battle armor, and probably most of the tech in the Underworld of ''WesternAnimation/Xyber9NewDawn''.
* ''WesternAnimation/AdventuresOfTheGummiBears'' had this by the truckload, most of it left behind by the enigmatic Great Gummis. The modern Gummis had some of it - like the Quick Tunnels - from the start and could use others as the series progressed, but they kept finding more and more powerful stuff, like the [[CoolBoat Gumarine]] and [[WaveMotionGun Gummi]][[PowerOfTheSun -Scope]]. Not even they were able to figure out how all of it worked, and a lot of it ended up destroyed. ([[NoManShouldHaveThisPower Which was often for the best, ironically]].)
* In ''[[WesternAnimation/{{Thundercats 2011}} [=ThunderCats (2011)=]]]'' the [[{{Catfolk}} Cats]] of the magical [[TheKingdom kingdom]] of Thundera, stuck in MedievalStasis, consider technology to be the stuff of [[OutgrownSuchSillySuperstitions fairy tales they tell their cubs]], and any physical evidence thereof as WorthlessYellowRocks forged to take in the gullible. Young Prince Lion-O believes otherwise, and scours the BlackMarket for [[BlackBox salvaged tech]]. Unfortunately, technology is very real, as their longtime rivals the [[LizardFolk Lizards]] prove when they ally with a benefactor to unleash a SuperWeaponSurprise, using shockingly ''futuristic'' war-tech like HumongousMecha and laser rifles to conquer the Kingdom of Thundera in ''one night''.

[[folder:Real Life]]
* A great many of the Romans' construction techniques, such as how to make aqueducts, were lost for centuries once the Roman Empire collapsed, and the remains are still around today.
** The Romans had used concrete to create buildings with domes. Once the Western Roman Empire fell, no large-domed buildings were able to be built until Brunelleschi's Cathedral of Florence was completed in the Renaissance. There were domes in the Middle East before the Renaissance, however, as they were inspired by the Hagia Sophia and other Byzantine churches. One of the reasons the secret of concrete was lost was because the Romans used a specific type of Italian volcanic ash as a binding agent. Attempts to duplicate the concrete recipe without access to that ash would fail, until a substitute was developed in the 1600s. Even modern concrete isn't quite as durable as the Roman type; some Roman buildings are still standing after 13 centuries or more.
*** Modern chemistry can replicate Roman concrete, but no one these days wants to pay the premium for a building that will endure like the Romans' did. Reinforced concrete is stronger than Roman, even when it's cheap Ordinary Portland Cement instead of Roman ''opus caementicum'', but it rots in 30-40 years unless it's reinforced with nonferrous materials -- which are much more expensive than steel rebar. The US Interstates, and doubtless other developed-world highways, are built on a foundation of concrete reinforced with fiberglass, which will last forever; but everything else contemporary will crumble pretty quickly.
** As part of their construction process, the Romans sacrificed animals and mixed their blood with the concrete, asking their gods to hold up the structure. No Christian would sacrifice an ox to ask Apollo and Dionysius to hold up a building, because it was asking for help from either imaginary beings or evil spirits; no scientist would ask for favors from Apollo and Dionysius either, because it wouldn't work. But it turns out it ''did'' work: [[RightForTheWrongReasons the blood aerated the concrete, and aerated concrete wears slower and lasts longer]]. (Dramatically slower and dramatically longer: many Roman concrete buildings are still perfectly serviceable today, while all concrete buildings built between the end of animal sacrifices for buildings, and the beginning of modern aeration, have already crumbled away.) Aeration was discovered as a formal principle in the 1940s-1950s, and it wasn't long afterwards that people realized that this is what the Roman animal sacrifices did.
** Also, depth in paintings; if you look at some of the murals from Pompeii, they might well have been painted in the 1600s for how realistic they look.
* A conspicuous aversion to this: the Medieval Industrial Revolution of the 1200s. This period gave us water mills, windmills, bellows, clockworks, pulleys, and camshafts: the machinery that the Industrial Revolution proper would automate. Fernand Braudel estimates that these machines gave Europe 2 or 3 million horsepower of automatic work; that isn't very much (men and horses gave Europe about 100 million horsepower), but it gave the continent its decisive edge.
* Another conspicuous aversion: during the so-called 'Dark Ages', the first universities were founded and punctuation and spacing between words was invented (while this might seem like a minor invention, it made books far easier to read).
* So-called "Damascus" steel has been lost for centuries since the original iron deposits in India ran out (there was a key impurity in those particular iron deposits). It was figured out in the late 1990's in Finland and there are now companies making bladestock from it. Modern bladesmiths have slowly been using it more and more. To prevent confusion with "Pattern-welded" steel, which was and is commonly referred to as "Damascus" steel, it is known by the original name for the ore: "Wootz".
** Likewise, the pattern-welding itself was almost lost after the Middle Ages. It was kept alive by rifle barrel makers until metallurgy became a science instead of arts.
* There is also the steel made from the Haya people, a tribe that existed in what is modern day Tanzania. They made [[http://www.uh.edu/engines/epi385.htm their]] steel in a kiln from the clay of termite mounds and shaped it like an upside-down cone. Their process required a mixture of charcoal, swamp reeds and iron ore, roasted at gradually rising temperatures as air was pumped into the kiln. The result was a high grade carbon steel which had been used by the Haya for 2,000 years or more before European steel had become mass produced, and the art of making the Haya steel was all but lost.
* There is also GreekFire, the secret weapon of the UsefulNotes/ByzantineEmpire, which could not be put out using water, of which the formula has been lost for ages. Today the problem of finding out what it was is more related to the fact that there are several options. There is more than one known way to make fire that can't be put out with water, as well as conflicting accounts of how Greek Fire actually behaved; some say it ignited on contact with water, others say it only needed to be exposed to air. Quite possibly it's a catch-all term for a number of different incendiary chemicals, some or all of which may have since been rediscovered.
* The [[http://en.wikipedia.org/wiki/Antikythera_mechanism Antikythera mechanism]] was a mechanical device for [[http://www.math.sunysb.edu/~tony/whatsnew/column/antikytheraI-0400/kyth1.html computing the position of the Sun, Moon, and the planets]] from a date and time. Its parts are on par with 18th century clocks in terms of complexity. It was made in the ''2nd century BC''.
* A tool similar in exquisite manufacture, reputation, mystique and expense to a classical-age violin is the classic double rifle from the golden age of African hunting. Contrary to what people may think, their number during TheEdwardianEra was never large (the vast majority of hunters and workers in the African colonies [[CaptainObvious could not afford something more expensive than a demilitarized rough and tumble bolt-action rifle]]) and insane expenses are needed to achieve in modern times the same performance it did 100 years ago. One may find out the hard way the $120,000 classic rifle once fired by [[Film/OutOfAfrica Denys Finch Hatton]] needs a caliber which no factory has built since the 1950s, is regulated to a precise combination of powder (which is no longer manufactured) and bullet weight and aerodynamics that no archive search can find, and finally the modern target shooter lacks the GreatWhiteHunter's talent, or is so different in body shape the rifle doesn't fit him or her the slightest bit.
* Swordmaking. The European style sword was never a constant style of design, but reflected the contemporary era; of fighting styles, armour and enemies it was designed to dispatch. Once new designs were introduced, old ones were lost. The Medieval style swords were successfully duplicated only in the late 20th century by the X-ray crystallography, metallurgical analysis and also analysis of sword physics.
* Cuir-bouilli. This is Medieval art of hardening vegetable-tanned leather into rigid and solid three-dimensional objects. These objects do exist, but the actual process has been lost. Modern experiments have produced similar, but not quite the same, objects. Likewise, the actual chemical process behind this art is still unresolved.
* The so-called [[http://en.wikipedia.org/wiki/Baghdad_Battery Baghdad Batteries]] (which are technically galvanic cells, not batteries). While significantly less powerful than that 99 cent Duracell you buy at 7-11, and requiring an entire vase (not a cheap item in those days), they were fully functional 1800 years ago. Naturally, this raised the question of why people made them in the first place. While no one actually knows for sure what their intended purpose was; archaeological evidence indicates that they were most likely used for electroplating gold (which would not require a large current); alternately, they could've been used to [[BoltOfDivineRetribution shock those who touched a religious object]].
** ScienceMarchesOn: Archeologists now beleive that they are not in fact batteries but were in fact storage vessels for sacred scrolls.
* The schematics for the Apollo vehicles, which were written on computers that no longer function, and cannot be read with modern computers. See NoBackwardsCompatibilityInTheFuture. NASA engineers are forced to go to junkyards looking for the original parts from the missions. They then have to, effectively, reverse-engineer the designs based on the plans they don't quite understand (to be clear, they may understand that the part in the plan is a valve, but they have no idea ''why'' it's there, which is more important).
* The A-10 Thunderbolt, only 715 of which were made, and in part has NoPlansNoPrototypeNoBackup ([[http://www.globalsecurity.org/military/systems/aircraft/a-10-maintenance.htm see here]]; the plans existed, but many of them were thrown away after the subcontractors went out of business), so there was a time when spare parts had to be scavenged from non-functioning planes.
** It's no secret that Generals of the US Air Force have long desired to keep replication of the A-10 lost, with their greater intentions to terminate the warplane's program entirety (for a laundry list of reasons and counterarguments too long to mention). To their dissatisfaction, pushback from politicians and ground soldiers saved by the A-10 has led to Congressional funding for reverse engineering of the A-10 blue prints to construct new parts. Boeing for example, [[http://www.boeing.com/defense/support/a-10-wing-replacement-program/index.page currently constructs new wings]]. Motor and electronic components are also being manufactured by other defense contractors, though the list gets hazier due to military secrets.
* Nowadays there is an entire branch of archaeology dedicated to fabricate and use replics of ancient tools just to determine what the heck were they used for. It has helped greatly to understand prehistoric lithic industries, though there are still items of unclear function, such as the palaeolithic "sceptres" found in many places.
* Techniques for forging relics? Maybe. Most medieval forgeries, like the Donation of Constantine, contain obvious mistakes. The Shroud of Turin might be a more convincing fraud; carbon dating turned up a late date, but the shroud had been damaged in a fire and repaired in the Middle Ages, messing with carbon-dating results. If the shroud really is a forgery, it's quite remarkable that medieval forgers knew to add first-century Levantine pollen to it, and even more remarkable that they had a supply of first-century Levantine pollen in the first place (although there's nothing stopping a 14th century forger from starting with a first century cloth).
* Heron Alexandrinus (10-70 AD) made (supposedly first): [[http://www.mlahanas.de/Greeks/HeronAlexandria.htm steam turbine]] -- ages before the piston steam engine that first got on trains and boats; several self-regulating feedback control systems -- precursors of things like the regulator which made possible the steam engine (and again) as today know it; and a vending-machine -- drop a coin, get a drink.
* Heron also described earlier (attributed to Archimedes) inventions, including an odometer, both in taximeter and naval log variants.
* According to Aristocles (2nd centrury BC), there was an alarm clock in Plato Academy.
* Around 424 BC Boetians burned down wooden walls of Delium. With a bellows-powered flamethrower.
* Aside of an organ (hydraulis), which was the first keyboard musical instrument ever -- and, by the way, [[OlderThanTheyThink quickly found its place as a church organ]][[note]]in the temple of Venus[[/note]] -- Ctesibius invented: a pump (ironically, it was lost in the fires that ravaged Alexandria); a water clock (a direct precursor to the flushing toilet); solar-powered mechanisms and a pneumatic cannon. In the third century B.C.
* Archimedes, according to Leonardo da Vinci, also built a steam-powered cannon.
* The Chinese [[AutomaticCrossbows magazine-fed crossbows]] (Chu-Ko-Nus) are rather famous, but there were more advanced forms. The first known chain-driven weapon was not "Chaingun", it was the chute-fed [[http://www.google.com/search?q=%2BDionysius+%2B%22repeating+catapult%22 Repeating Catapult by Dionysius of Alexandria]].
* Mobile artillery has been repeatedly lost and reinvented. Consider the Roman ''ballista quadrirotis'', two-horse cart with a ballista on top.
** Also, tanks. The first ''Panzerkampfwagene'' were used by the Hussites; they were literal armored fighting wagons, drawn by horses and carrying an artillery piece and ten or so soldiers (armed with flails and muskets) apiece. On the defense, they "circled the wagons", connected them with chains, and easily repelled knightly charges; on the attack... we're not sure, but with a defense like that, they hardly needed to attack.
* UsefulNotes/GotzVonBerlichingen, the knight most renowned for his wit due to [[Creator/JohannWolfgangVonGoethe Goethe's]] [[Theatre/GotzVonBerlichingen homonymous play]], had a mechanical prosthetic iron hand to replace [[HandicappedBadass his right hand and forearm lost in combat]]. It was so advanced anatomically that it could handle the reins of a horse, the shaft of a lance, a playing card and even a feather quill to write a letter. But there was one thing the 16th century lacked -- the energy source (springs would be either too weak or too big) -- the hand needed first to be tightened by the other hand around the object to be handled.
* The field transistor predates the bipolar transistor by 22 years (Lilienfeld filled the first patent application in 1925), since the idea was much closer to the electron tube. It's unlikely that he really ''built'' it: considering the proposed scale and the quality of early semiconductors, it would not give a measurable amplification. But the principle ''was'' right, even though the theoretical basis was not yet developed.
* Another Chinese example would be the [[http://en.wikipedia.org/wiki/South_Pointing_Chariot south-pointing chariot]], a mechanical compass working on principle of Cardan gear.
* The [[PyramidPower pyramids]] of AncientEgypt. Even today, there are scholars who argue as to how the ''pre''-Bronze-age Egyptians moved all those multi-tonne stone blocks into place. (Since the advent of pourable concrete, the manipulation of enormous solid pieces of stone has basically become a lost art.) It's an odd example since the Egyptians actually left illustrations of some parts of the construction process, but generally not the parts there's any reason for confusion about.
* Stonehenge. Not only is the technique of arranging the stones unknown, but there's also the matter of how they actually got the stones to the site in the first place, as scientific study has determined that the type of stone used is from Wales, several hundred miles away. While modern technology would make this fairly easy to do, Stonehenge was built '''5,000''' years ago. There is also the question as to what the site is actually for, with several theories ranging from credible (some kind of calendar/clock system, religious significance) to... less so (aliens).
* Future Lost Technology in the works: The Clock of the Long Now is being designed and built to run for 10,000 years.
* The medicinal and culinary herb silphium, extensively used by Mediterranean cultures in classical times, was widely believed to have gone extinct around the time of Nero. As it's unclear precisely what silphium actually ''was'', researchers don't know if its suspected living relatives (asafoetida and giant Tangiers fennel) are the same plant under another name, or if it really did die out from over-harvesting and overgrazing of the Libyan coast.
* Another biological mystery of the ancient world is the North African elephant, described as a buffalo-sized version of the African bush elephant, which is reputed to be untameable. Was it a subspecies of the latter, or a different species altogether? What exactly did the ancient Numidians and Carthaginians to train them? In the early 1900s the Belgians managed to train African forest elephants (now recognized as a different species) in the Congo, however, using the same techniques employed in South-east Asia to train Asian elephants. It is possible then that the North African elephant, like the forest elephant, was just small enough to be manageable, unlike its gigantic savanna brother.
* There are cases of prehistoric peoples that colonized islands by boat, probably first discovering them in fishing trips to the ocean, and then stopped making boats and fishing altogether, even from the shore. For a while, the ancient Tasmanians were believed to have even forgot how to make ''fire'' - and while that has been fairly well debunked, it has been proved that they reverted from shaped bone tools to sharpened stone ones.
* When the British first met the Lumbee people of North Carolina in the 18th century, they were told that their ancestors could "talk in a book" and "make paper speak", but they no longer did. One theory is that the Lumbee tribe absorbed the survivors of the English colony of Roanoke, which disappeared with barely a trace around 1589.
* Writing was completely lost during the Greek Dark Ages (ca. 1100–800 BC). The later Greek alphabet is an adaptation of the Phoenician alphabet, adopted at the end of that era.
* Throughout much of Russia there are upwards of a hundred known abandoned scientific facilities that don't have an exact known purpose and quite isolated. It is more than possible that one of these stumbled on a major scientific breakthrough that was lost in the fall of the Soviet Union, even when one does not consider that there are more than likely even more interesting labs that modern society does not know about.
* Like with the Russian abandoned laboratories mentioned above, several of Nazi Germany's scientific facilities weren't discovered until decades after the end of the war and their contents had long decayed.
* The Russian answer to the American Space Shuttle, the [[http://en.wikipedia.org/wiki/Buran_%28spacecraft%29#First_flight Buran program]] was canceled with the collapse of the USSR. The first shuttle had made its first and only space flight in 1988, before being put along with the other unfinished ships into undetermined storage, scavenged for parts and ultimately forgotten. What was left of the one flown Buran was destroyed in 2002, when its hangar collapsed upon itself because of lack of maintenance. What makes this tale even sadder? The Buran was ''more'' advanced than the Space Shuttle, and could fly unmanned (which doesn't change the fact that the shuttles were clearly an evolutionary dead end).
* Avro Canada had actually made working versions of many stereotypical "Sci Fi" concepts like flying cars, but when their flagship project [[CoolPlane the Avro Arrow]] [[TheGreatPoliticsMessUp was sunk]], the company broke apart and the blueprints and prototypes were scrapped for national security reasons. There are even parts of various Avro projects being found and rumors of others.
* The [[http://en.wikipedia.org/wiki/Flush_toilet#History flush toilet]] has been invented at least two dozens times, and lost at least half of that. One of its earliest users, the Indus Valley Civilization (26th century BC) also had a sewage system whose complexity wouldn't be matched until Roman times.
* The use of Vitamin C as a cure for scurvy was discovered and lost several times before the 20th century.
* While not exactly technology, the Destrier Warhorse is an extinct breed, as their key traits, such as their aggressive, energetic temperament and their strength made them unsuited for roles of a peacetime steed or workhorse.
** The same fate has befallen a number of other domestic animal breeds whose original functions are no longer needed. For example, the "turnspit" was a British breed of dog once used to generate HamsterWheelPower to rotate skewers of roasting meat: a function long since subsumed into mechanized and convection ovens.
* In 1986, the BBC Domesday Project implemented a fully interactive and searchable database of the Domesday census books. The project's hardware used an [[https://en.wikipedia.org/wiki/BBC_Master Acorn BBC Master System]] which was state-of-the-art in its day, but was not widely purchased by the British public. As years passed, [[TechnologyMarchesOn machines that could read the project were becoming rare]], and fears of digital obsolescence [[KeepCirculatingTheTapes spurred on efforts to preserve it and make it accessible from the Internet]].