->''"Then they went out and played Charles Fort and the Atlanteans versus the Ancient Masters of Tibet, but the Tibetters claimed that using mystic ancient lasers was cheating."''
-->-- ''Literature/GoodOmens''

Almost no matter what your level of military tech- javelin, arquebus, [[Film/TheTerminator phased plasma rifle in the 40 Watt range]], quantum black hole, whatever - it's nowhere near as good as it was in your [[TheyDontMakeThemLikeTheyUsedTo great-great-granddad's day]]. In those days, men were real men, women were real women, and hideously powerful destructive forces were... better than this modern muck, with [[PowerGlows glowing]] [[InstantRunes runes]] and everything. This could be despite the [[SuperweaponSurprise apparent primitive nature]] of the society at the time. More rationally, it could also be [[AndManGrewProud the cause]] of the primitive nature of the society immediately following...

In any event, unlike its cousins the AncestralWeapon and ForgottenSuperweapon, the LostSuperweapon is [[ExactlyWhatItSaysOnTheTin lost]], not just possessed by someone in secret. (For the latter, see SuperweaponSurprise.)

Lost Superweapons are generally a type of PlotCoupon and found in fantasy novels and video games. If the Lost Superweapon has become a notable part of the landscape, then it is a WeaponizedLandmark. If it was lost with the intent of it never being found again but is found anyway, it's a DangerousDeviceDisposalDebacle.

See also: MacGuffin, ArtifactOfDoom, OlderIsBetter, SuperPrototype, LostTechnology and DangerousDeviceDisposalDebacle. Compare FlingALightIntoTheFuture.


[[folder: Anime & Manga]]
* ''Anime/MazingerZ'': Mykene Mechanical Beast. Old myths assured an ancient, [[spoiler:allegedly]] lost Greek civilization called Mykene lived on the island of Bardos used [[HumongousMecha metallic giants]] [[ChestBlaster shot flames from their chests]] to defend their land. BigBad and MadScientist Dr. Hell pondered maybe the myths might be true. Unfortunately for everybody, the old legends were indeed right, and he found an army of ancient, forgotten HumongousMecha under the ruins of the island. However it is a subversion, since [[spoiler:like it was seen in ''Anime/GreatMazinger'', the Mykene civilization still existed, and throughout millennia had dramatically improved their technology, and compared with their newest mechas, the giant robots Dr. Hell found were ancient, outdated, mountain sized piles of scrap.]]
* ''Manga/OnePiece'' has, as part of its MythArc, the existence of three super weapons, Pluton, Uranus, and Poseidon that are so powerful they make the Marine's Buster Call (which is an order to summon ten massive battleships to an island to incinerate it) look mundane. They are so rare, powerful, and difficult to obtain that one villain tries to conquer an entire country ''just to facilitate finding one.'' So far we know Pluton is a battleship of some kind and Poseidon is [[spoiler: the Mermaid Princess' ability to command the Sea Kings]].
* The God Warriors of ''Manga/NausicaaOfTheValleyOfTheWind''.
* The [[CoolStarship Saint's Cradle]] of ''Anime/MagicalGirlLyricalNanohaStrikers''.
** And [[PersonOfMassDestruction Ixpellia]], who was in suspended animation for hundreds of years.
* ''Anime/MacrossZero'' centers around a [[{{Precursors}} Protoculture]] artifact known by the UN as "AFOS" and by the native Mayan islanders as "the bird-man". The militaries of both the UN and Anti-UN believe it is a powerful weapon and wish to use it, while the islanders believe that the bird-man is an ancient deity whose awakening will trigger [[TheEndOfTheWorldAsWeKnowIt the end of the world.]] [[spoiler:The truth is a bit of both: the Protoculture did not want humanity to repeat their mistake of bringing war to the greater galaxy. The bird-man was an AmbiguousRobot they left behind whose job was to annihilate humanity if humans had not turned pacifistic by the time they achieved space travel. [[FromBadToWorse And it just got woken up in the middle of a World War.]]]]
* In ''Anime/GargantiaOnTheVerdurousPlanet'', the humans on Earth salvage what they can find underwater in wreckages and remains of ancient human civilization. They end up finding things such as laser cannons and railguns, which are much more advanced than the guns and artillery they've been relying on. And despite said lost weapons, all of that pales in comparison to what Ledo and Chamber, his AI mecha support, have. Which makes sense because said lost weapons were very old precursors to what was eventually built into Chamber, after the two were stranded during a retreat from a battle in outer space a long distance away from Earth.

[[folder:Comic Books]]
* Franchise/{{Superman}}:
** ''Comicbook/WarWorld'': Superman and Comicbook/{{Supergirl}} have to destroy Warworld, a star-sized weapon-satellite built by a war-mongering alien race several centuries ago.
** ''Comicbook/KryptoniteNevermore'': A mysterious instrument called the Devil's Harp that can steal someone else's powers and skills and transfer them to its owner was found hidden in an ancient buried city.

[[folder:Fan Works]]
* ''Fanfic/TheNewAdventuresOfInvaderZim'' has an {{invoked|trope}} example with the Meekrob device known as [[WeaponOfMassDestruction Project Domination]]. The other Meekrob were so offended by its existence that they imprisoned its [[MadScientist creator]] and sent it to drift in space so no one would find it.

* The Great Cannons in ''Film/LegendOfTheTsunamiWarrior'', which sank to the bottom of the sea and were retrieved by a band of pirates. An usual example in that they were only lost for a couple of decades.

* ''Franchise/StarWarsExpandedUniverse'':
** The novels have [[spoiler:the entire solar system of Corellia, made of giant spaceships disguised as planets with the tiny station of Centerpoint being the control center. Said spaceships can attack with their giant repulsors/engines, and Centerpoint is able to warp gravity across the galaxy to decimate an entire alien fleet. Oh, and Centerpoint can also make stars go nova and cut off the Corellian system from access to hyperspace. It's indicated (though never attempted) that by using the planetary repulsors to boost Centerpoint's output, the station could cut the ''entire galaxy'' off from hyperspace, making it all but impossible to travel between star systems. Given how essential interstellar travel is in the ''Star Wars'' universe, this would be roughly equivalent to reverting Earth to the stone age at the press of a button.]] Subverted, in this instance, as there's reason to believe that ThePrecursors didn't originally build this particular LostTechnology to be used as weapons of war. [[spoiler:In part, it was designed to make sure a SealedEvilInACan stayed in its can.]]
** Other examples include the Sun Crusher (which was forgotten because it was built in a remote Imperial wormhole facility that was only known to three people outside the facility...only one of whom was still alive), the Katana Fleet (which was lost to hyperspace troubles) and the ''Lusankya'' [[spoiler:(an entire Super Star Destroyer buried beneath Coruscant to use as a prison)]]. It's never specified why the latter was forgotten, but the two theories offered in-universe are both horrifying: [[spoiler:that [[BigBad Emperor Palpatine]] was able to block everyone's memories of its burying through the Force, or that [[LeaveNoWitnesses he simply had all of the billions of witnesses killed]].]]
** The Eye of Palpatine, a largely autonomous superweapon predating the Death Star with the mission of destroying a colony of fugitive Jedi. It never completed its mission due to sabotage, and was forgotten by Rebels and Imperials alike (those that even knew about it in the first place) until mysterious forces cause its AI to suddenly awaken.
** The Another Chance, an Alderaanian warship loaded with ''[[MoreDakka every weapon on the planet]]'' when Alderaan decided to disarm itself, and sent off into deep space where it would be virtually impossible to find.
** PersonOfMassDestruction Irek Ismaren, a Dark Jedi with implants that allow him to control droids and computers. Virtually unknown even within the Emperor's inner circle until ''Children of the Jedi'', then disappears from galactic history ''again'' [[spoiler:until Luke encounters him again as Lord Nyax - 3 meters tall, wielding no less than 6 lightsabers permanently attached to his body.]]
* ''Literature/TheLordOfTheRings'' is ''full'' of these. Indeed, the book is set against a backdrop of general technological decline. If you're going into battle wielding anything forged within the last 3000 years or so, you might as well run into an aeroplane propeller.
** And, as the trope description indicates, the constant war that produced these weapons is indeed the reason that things have fallen so far. For all Minas Tirith is impressive, it used to be a border fort and is beside the ruins of the fallen city it used to protect.
* Subverted in Creator/AlastairReynolds' ''Literature/RevelationSpace'' universe: In one book, several of the heroes spend most of the story on a race to track down and wield Lost Superweapons to turn on the remorseless alien foe. They probably hoped for better results than [[spoiler:"none at all. But she went out with a bang"]].
* Creator/AlanDeanFoster's ''Literature/HumanxCommonwealth'' universe is loaded with {{Phlebotinum}} left behind by [[{{Precursors}} ancient civilizations]], among them quite a few superweapons. Examples:
** The title device in ''The Tar-Aiym Krang'', which uses an entire planet as its power source and creates [[{{Technobabble}} Swartzchild discontinuities]]... ahem, miniature black holes that utterly annihilate anything they touch.
** The Hur'rikku artifact in ''The End of the Matter'', which uses a powerful stasis field known as [[{{Technobabble}} Fixed Cosmic Inertia]] to slingshot itself through spacetime and punch a hole into AnotherDimension, through which a "white hole" composed of pure antimatter is created. This is used to destroy rogue black holes.
** Not satisfied with one Krang, the Tar-Aiym also built a weapons platform the size of an entire planet that contains hundreds of Krangs. Flinx discovers it in ''Reunion'' and spends the rest of the series searching for it. [[spoiler:His attempt to use it against the UltimateEvil ends up being a [[TheWorfBarrage Worf Barrage]]]].
** And last but certainly not least, the Xunca. Not satisfied with destruction on a mere planetary or solar system scale, they constructed a weapon concentrating the energy of several million galaxies across multiple dimensions. ''It gets used.''
* The title device in Larry Niven's ''The Soft Weapon''.
* A large number of these in ''Literature/MortalEngines'', such as MEDUSA the [[spoiler:city destroying laser]] and [[spoiler:ODIN the KillSat]].
* Only a 30-year backlog on this one, but Peter F. Hamilton's ''Night's Dawn'' trilogy has the ''incredibly awesome'' Alchemist, which disappeared when the strike force heading off to deploy it was destroyed shortly before the genocide of their home planet's population. [[spoiler: It's recovered towards the end of the second book, ''The Neutronium Alchemist'', and the (fairly accurate) physics is explained- and we discover that it can turn a sun into a black hole. That's the ''more humane setting.'']]
* The Ma Wi Jung in ''Literature/CrystalRain,'' though [[spoiler: it's not exactly a super''weapon'', per se.]]
* In ''Literature/LifeTheUniverseAndEverything'', there was the Supernova Bomb. Invented by the supercomputer Hactar at the behest of the Silastic Armorfiends of Striterax, it was a junction box which would make every sun in the universe go supernova simultaneously. Hactar purposefully made it faulty because he calculated that there wasn't a conceivable consequence resulting from not setting it off which could be worse than the known consequences of setting it off, so... The Armorfiends disagreed, before destroying him and then, fortunately for everybody else, themselves. [[spoiler: Hactar managed to survive in a reduced form, and many millenia later had the Omnicidal people of Krikkit rebuild the bomb before planting it on Arthur Dent, who very narrowly avoided setting it off.]]
* ''Literature/TheWheelOfTime'' has a couple of these lying around. Most notably, there's the Choedan Kal, two artifacts so powerful that each of them is capable of not only destroying the world, but also causing serious damage to the fabric of reality itself.
* In Christopher Rowley's ''Starhammer'', The title weapon is a huge skyscraper-sized tank carrying a weapon that blows up stars, instantaneously over unlimited ranges.
* Iain M. Banks's ''Against A Dark Background'' features a Lazy Gun as a MacGuffin.
* The Hador-Haelic space forts from ''Literature/TheHelmsmanSaga''. They are well remembered and in plain sight, actually, and still in pristine condition after thousands of years... it's just that no one remembers how to power the guns up.
* The titular artifact in ''Literature/DarkHeart''. An ancient magical weapon, capable of killing gods, that was used by the winning side in Caliel's long-ago Godswar, then lost when the victors had a falling out after the war.

[[folder: Live Action TV ]]
* The Dakara Superweapon in ''Series/StargateSG1'', which was originally used by the Ancients to seed all life in the Milky Way. Being the arrogant, NeglectfulPrecursors that they were, they decided that instead of dismantling the device afterwards, they'd simply leave it sealed inside of a mountain, guarded by a single locked door.
** When the protagonists get their hands on it they use it the exterminate the entire Replicator species. Its suggested that it could be tuned to kill anything, or everything.

[[folder: Tabletop Games]]
* In one ''TabletopGame/{{Paranoia}}'' mission, the [=PCs=] discover a long-forgotten antimatter bomb capable of destroying the entire Complex, and have to keep it away from fanatics who would actually detonate it.
* This trope practically litters ''TabletopGame/{{Exalted}}'', with two major examples being the Five-Metal Shrike (a sentient warship from the First Age that is hinted to still soar the skies of Creation) and the Realm Defense Grid (an old superweapon which only one person has ever been able to master since the days the Solars ruled... and they ended up making that person Empress of the most powerful nation in the world once she was done with it).
** FMS might be nice, shiny and theoretically operational by just a playgroup, but there are also some surviving Directional Titans it was designed to kinda "replace". One is currently an [[VideoGame/BioShock underwater city]] and another a giant freaking flying mountain. Estimated matter survival time around each of those deployed in combat: 1 tick. And it does take a city of operators to man.
* This was the original defining feature of ''TabletopGame/BattleTech''. The golden age of technology was some 300 years ago and everything now is patched-up, dumbed-down versions of the stuff the Star League had but the Successor States have largely forgotten how to make. Later subverted [[ApocalypseNot as the Successor States slowly recovered]], putting them on par or beyond the Star league.
** The interstellar Warships have gone back to being lost, after the Word of Blake Jihad concluded. Every faction still has a few, but all the facilities capable of building more were destroyed and nobody's bothered trying to rebuild them. Inside the game universe, it was considered too expensive and difficult to maintain the facilities and there weren't enough people with the skills necessary to do so anymore. Outside of the game universe, WordOfGod is that the developers considered them to be overpowered compared to everything else and therefore wanted them to no longer be a factor: the HumongousMecha the game was supposed to be centered around risked being metaphorically and [[DeathFromAbove literally]] overshadowed if Warships continued being built and used by everyone.
* The Imperium in TabletopGame/{{Warhammer 40000}} appears to have lost the ability to innovate. Apart from reuniting humanity the Great Crusade is also about finding [=STCs=] on lost colony worlds that describe how to build things the Empire lost the plans of in the Age of Strife. There are also superweapons knocking about that were built by mysterious ancients who tend to manufacture these awesome devices and then wander off with the instruction manual in their pockets never to be seen again.
** In usual ''[=40k=]'' fashion, the trope is taken UpToEleven with technology from the aptly named "Dark Age of Technology", which was really a GoldenAge for humanity. One novel describes the Adeptus Mechanicus (a machine-worshipping cult and one of the forces keeping the Imperium running) and their ancient space ships, with one of them hooking up to the ship's systems, which accidentially reactivates the equally ancient weapons on board. In short, in a setting where a small fleet of space ships can destroy entire planets, they still managed to bring this trope, since the weapon activated turned out to be a kind of temporal rift space torpedo, which then destroyed a massive Eldar ship (about the size of the moon) in a ''single shot''.
* There are enough of these floating around in ''TabletopGame/RocketAge'' that its a serious problem. Mostly left over from the war between Mars and Eris, they seem to crop up in most of the adventures.


[[folder: Video Games]]
* In ''VideoGame/{{Journey}}'', the creatures you encounter in the fifth and seventh levels are [[spoiler:the machines responsible for starting a civil war against your ancestors. Only some units remained active after the war]].
* [[spoiler:Vegnagun]], the semi-sentient, [[EarthShatteringKaboom Earth Shattering]] [[DoomsdayDevice Doomsday]] [[WaveMotionGun Gun]] from the final days of ''VideoGame/FinalFantasyX'''s Machina War, was sealed deep below Bevelle one thousand years ago. [[VideoGame/FinalFantasyX2 Then it goes missing]].
* {{Orichalcum}} is an ancient Atlantean superfuel/explosive in VideoGame/IndianaJonesAndTheFateOfAtlantis. Eventually Indy discovers what the Atlanteans powered with the orichalcum: [[spoiler: a god making machine]].
* ''Franchise/{{Halo}}'' has lots of these, courtesy of the Forerunners:
** The titular ringworlds, which kill all sentient life in the galaxy when fired at once.
** ''VideoGame/{{Halo 4}}'' features the Composer, [[spoiler:which downloads organic beings and reconstructs them into mechanical Promethean Knights]]. Unlike most examples, it was not originally intended to be used as a weapon; even the "[[spoiler:turn people into robots]]" part was not part of its original purpose.
** ''VideoGame/Halo5Guardians'': The titular Guardians, gigantic bird-like constructs buried in numerous worlds. Now they're all awakening from their 100,000-year-long slumber in order to police the galaxy again.
* Remember the Gaia Temples in ''VideoGame/SonicUnleashed''? The ones built centuries ago to house (and if needed restore) the power of the Chaos Emeralds? Well, apparently, [[spoiler:Light Gaia/Chip can summon them to form the Gaia Colossus, the one integral component (aside from the power of the emeralds) needed to tame [[EldritchAbomination Dark Gaia]] and prevent TheEndOfTheWorldAsWeKnowIt.]]
** In fact, this was [[DubNameChange Dr. Egg...er, Robotnik's]] shtick from about VideoGame/SonicAdventure to Sonic Unleashed (chronologically, about 1998-2008). Virtually every storyline had him digging up one deranged EldritchAbomination--or OneManArmy, in [[VideoGame/SonicAdventure2 Shadow's]] [[VideoGame/ShadowTheHedgehog case]]--or another. Of course, [[TheStarscream they all had their own agendas]], usually revenge on whoever imprisoned them in the first place.
* In ''VideoGame/StarCraftII'', protagonists [[TheHero Jim Raynor]] and [[TheLancer Tychus Findlay]] are hired to recover several seemingly benign-well, relatively benign-[[ThePrecursors precursor]] artifacts for an interested party. As it turns out, the five artifacts are actually the [[spoiler: [[DismantledMacGuffin parts]] of device capable of killing all the zerg an entire region of the planet Char, and curing [[TheVirus zerg infestation]]]].
* The contents of D-6 in ''VideoGame/{{Metro 2033}}'', especially the [[spoiler:[=MRLs=] used to destroy the Dark Ones' hive.]]
* Deconstructed in ''VideoGame/MetroLastLight'' where Rangers are trawling the D-6 storage facilities for survival supplies, but all they can find are bioweapons stockpiles. Lo and behold, some of those bioweapons end up in the wrong hands and nearly cause a catastrophe.
* [[spoiler:Guillo]] in ''VideoGame/BatenKaitosOrigins''. It was lost after the defeat and death of Malpercio, and the Children of the Earth abandoned it, feeling that a weapon capable of killing a god wasn't something the new world would need.
* The B-plot of ''VideoGame/MassEffect3'' involves the Alliance trying to recover a Prothean superweapon, the Crucible, to use against the Reaper invasion. There are only two wrinkles: one, it's some-assembly-required, given that they have only the blueprints; two, it is missing a crucial component, the Catalyst (which is why it didn't work for the Protheans) -- [[spoiler:which turns out to be the Citadel]].
** ''Mass Effect 3'' deconstructs this trope, [[spoiler:as the designs for the superweapon are revealed to predate the Protheans - and even their predecessors - with every cycle adding and improving to its design. The last several of those cycles built it out of desperation from recovered plans and had no idea what the hell it was actually supposed to do.]]
* The Cetan starship from ''VideoGame/PerfectDark'' is a [[EarthShatteringKaboom planet killer]] that has been resting on the floor of the Pacific Ocean for millennia. The plot revolves around a conspiracy to retrieve the weapon and use it on Earth.
* There are a few in the ''VideoGame/{{Homeworld}}'' games. ''Homeworld: Cataclysm'' has the Siege Cannon, a WaveMotionGun built millennia ago by the [[spoiler: Bentusi]] and then abandoned when the [[spoiler: Bentusi]] disarmed themselves. Also, ''Homeworld 2'' has the Movers, the Progenitor Dreadnoughts and the warship [[spoiler: ''Sajuuk'']], all built by the Progenitors before their disappearance. These are the ones the player can acquire, as all the games have one: the original ''Homeworld'' has the Junkyard Dog (the most annoying foe in the series, possibly a Progenitor Mover variant), ''Cataclysm'' has the ''Naggarok'' (and if the damn thing had stayed lost until you found a way to destroy it, the characters would have been happier), and ''Homeworld 2'' has the Progenitor Keepers, the drones carried by the Keepers and the [[ExactlyWhatItSaysOnTheTin Planet Killers]] (these of unknown origin, but somehow linked to the [[spoiler: Bentusi]]).
* In ''PickleWars'', the hero is tasked with finding the secret stash of weaponry needed to defeat the aliens that have invaded Arcadia. The weapons are lost because Arcadia has achieved world peace and has not had any need for them in ages.
* Subverted in ''VideoGame/TheAdventuresOfMassmouth'', where the mythical magical superweapon (the "Eye of Mahan"), once found, turns out to not do anything at all.
* A [[SufficientlyAdvancedAlien Yithian]] lightning gun is found in ''VideoGame/CallOfCthulhuDarkCornersOfTheEarth'' just [[DarkestHour when]] it's needed most.
* ''VideoGame/{{Fallout 3}}'' has Liberty Prime, a giant robot originally built for the Anchorage Reclamation in 2072, but kept idle due to power supply difficulties. After the bombs fell, it stood forgotten in the Pentagon ruins until the Brotherhood of Steel arrived. They finally get it up and running for the battle to take back Project Purity from the Enclave. And then blown up by a KillSat controlled by Enclave. [[spoiler: They managed to rebuild it in ''VideoGame/{{Fallout 4}}'' in order to destroy The Institute, but it can potentially be hacked and turn on the Brotherhood depending on who the player wants to side with.]]
** ''VideoGame/FalloutNewVegas'' has one hidden in plain sight: HELIOS One, a large solar power plant that's also linked up with a KillSat called Archimedes II. The Courier can decide whether to reactivate the connections to Archimedes II or strictly use it as it was originally designed, leaving said superweapon forgotten.
* These appear in ''VideoGame/DistantWorlds'' as discoverable technology from ruins in any planet that is not a gas giant and they can be reverse-engineered as usable equipment for your warships. Access to such weapons can [[LensmanArmsRace greatly shift the balance of power among races]] as you now have a fearsome OneHitKill weapon to easily win your battles.
* Some stuff of Precursor origin in ''VideoGame/StarControlII'', most notably the Sa-Matra battleship -[[spoiler: that [[CurbStompBattle curb-stomped]] the Alliance fleet at the end of the war in the hands of the Ur-Quan]]- and the Utwig Bomb, able to destroy a planet. [[spoiler: You must use the latter to destroy the former]].
* The Old Sentinel from ''VideoGame/{{Battleborn}}'' is a legendary ancient artifact/doomsday weapon that's based on Ekkunar for at least a thousand years, probably zillions according to Mellka. Originally thought to be just the stuff of stories, Rendain was able to find its location and decided to acquire it. The objective of '''The Sentinel''' mission is thus for the Battleborn to destroy the titular sentinel per the Eldrid Observatory's instructions as it was deemed better that it be dead than fall into Rendain's hands much to Mellka's dismay as she sees the Sentinel as a sort of childhood hero from the stories she heard about it.
* ''Franchise/TheElderScrolls'':
** ''[[VideoGame/TheElderScrollsIIDaggerfall Daggerfall]]'' has the Numidium, a [[RealityWarper Reality Warping]] HumongousMecha of [[OurDwarvesAreDifferent Dwemer]] origin. In the series' backstory, [[GodEmperor Emperor Tiber Septim]] was given the Numidium by the [[PhysicalGod Tribunal]] of Morrowind in exchange for special privileges as a VoluntaryVassal. Septim used it to [[CurbStompBattle great effect]] in conquering the rest of Tamriel. After Septim began using the Numidium in ways not intended, one of his agents who helped him gain control over it destroys it, sending its power source outside of the mortal realm. ''Daggerfall'''s main quest has the player coming into possession of the control rod and power source for the reconstructed Numidium, and then deciding which of several competing factions gets to have the weapon.
** ''[[VideoGame/TheElderScrollsIIIMorrowind Morrowind]]'' has PhysicalGod BigBad Dagoth Ur discovering the blueprints for the Numidium and using them to construct his own mecha, Akulakhan, to be powered by the [[CosmicKeystone still-beating heart]] of the [[GodIsDead "dead" creator god]] Lorkhan. (Which is what the Dwemer originally planned to use to power the Numidium.)
** In general for the series, any Dwemer technology can qualify. They were by far the most scientifically advanced race on Nirn and learned how to bend the laws of nature and physics to [[RagnarokProofing make their creations last]]. Even thousands of years after their disappearance (believed to be related to their use of the aforementioned Heart of Lorkhan), intrepid scholars can use the abandoned Dwemer tech to accomplish feats no one else can match. Perhaps most impressively, the Dwemer were able to create a machine capable of reading the [[TomeOfEldritchLore Elder Scrolls]] without subjecting the user to the nasty side effects of blindness and madness.
* ''VideoGame/AVeryLongRopeToTheTopOfTheSky'': The God's Eye, when used as a city-destroying weapon, was lost in an area that was so sacred, it wasn't explored until the heroes found it. Or just how to make it was forgotten, given that the components to make another one can be found in other places. It's just that a complete one is in that lost location.

[[folder:Web Comics]]
* ''Webcomic/GirlGenius'': Subverted when the legendary Storm King returns from the dead bearing his LegendaryWeapon, only to have Simon Voltaire NoSell its effects. Voltaire points out that he's one of the intellectual descendents of the Spark who created the weapon in the first place, and has the benefit of two hundred years spent studying the operating principles of the weapon, improving on the design, and developing countermeasures.

[[folder:Web Original]]
* The [[{{precursors}} Iormunean]] [[PraetorianGuard Imperial Templar's]] blessed weapons from ''Roleplay/OpenBlue'' are [[SmiteEvil divine armaments]] enchanted with various elements and powers. Compared to the weapons of the present timeline, they're definitely superweapons.

[[folder:Western Animation]]
* Surprisingly (And hilariously) subverted in ''WesternAnimation/{{Ben 10}}'' when Enoch searched for an ancient Mayan sword. Grandpa Max had been so distracted by getting it first and keeping it from the wrong hands, it almost killed his grandchildren. With the final opportunity, he gave up the sword in exchange for saving Ben and Gwen's lives. Of course that means Enoch now has the sword... which turns to dust soon after he picks it up.
-->'''Max''': (Laughs after the sword turns to dust) Guess that's what happens when the world's most powerful sword is over 5,000 years old.
* The Sword of Ascanlon in ''WesternAnimation/Ben10UltimateAlien'' fares better [[spoiler: probably because it was made by alien technology]] and was used to cut out and contain the heart of an EldritchAbomination a thousand years before the series. Unfortunately, it (and the heart of said abomination) didn't stay lost.

[[folder:Real Life]]
* In the early days of World War 2, Britain was in dire need of large caliber heavy artillery to defend against a cross channel invasion. However, because the production lines to make such weapons had been dismantled after World War 1, new weapons of the same type could take ''years'' to produce from scratch. Records indicated that a number of large railway guns had in fact returned home from UsefulNotes/WW1, but, despite their size, had been "lost" in the intervening years. In November 1939, a Lt Colonel was sent on a quest to locate the guns and after months of fruitless searching he noticed a large disused railway shed at a Royal Ordinance depot. Forcing the doors open he discovered no fewer than 20 9.2" railway guns and 12" railway howitzers along with three additional 14" [[NamedWeapons named railway guns]] (Boche-Buster, Scene-Shifter and Gladiator). These were all promptly reconditioned and [[http://www.disused-stations.org.uk/features/index6.shtml put back into service]].
** Another story has it that a Royal Ordinance surveyor was inspecting a railroad line for suitable firing locations when he discovered another shed with a perfectly maintained 9.2" railway gun inside. A short while later an older man showed up and explained that he had been collecting a small stipend to look after the gun for the last 20 years.