[[quoteright:350:[[VideoGame/{{Grandia}} http://static.tvtropes.org/pmwiki/pub/images/wall_1.jpg]]]]
[[caption-width-right:350:[-When neighbors from another ''continent'' get too noisy.-]]]

All around where you grew up is a barrier. No one knows what lies [[TheOutsideWorld on the other side]]. Or if they do, they're not telling. It could be HereThereBeDragons, or your ancient enemies, or it could be that you and everyone you know is SealedGoodInACan (or [[SealedEvilInACan evil]], who knows?). Passage through will be difficult if not impossible, for what good is a barrier if anyone can walk on through?

The wall can surround a single village, a town, a continent, a world, or even [[CorralledCosmos an entire galaxy]]. Or it could seemingly surround nothing, and simply mark a barrier between one world and the next.

Note that, despite the name, the barrier does not have to be a literal wall.

If the barrier surrounds a community, it is an isolated SmallSecludedWorld or CityInABottle or possibly a DomedHometown. Contrast with TheGreatWall, which bisects the world, dividing it into two separate parts, and TheOutsideWorld, what lies outside the walls. When the wall is so big people start living on it, you have yourself a DysonSphere.



[[folder:Anime & Manga]]
* The wall around the town in ''Anime/HaibaneRenmei''. (We never do find out what lies beyond, though considering that the walls are [[spoiler:death]]...)
* In the first and second seasons of ''LightNovel/{{Slayers}}'', the world Lina could explore (and put craters into) was restricted by a magical barrier that went down after the BigBad powering it was killed.
* The wall in ''Anime/PrincessTutu'' is both literal and metaphorical, keeping reality from intervening in the [[TheoryOfNarrativeCausality narrative-controlled]] Gold Crown Town. Most people don't even realize it exists, since the story prevents them from wanting to leave. (This doesn't stop people from suddenly appearing inside the town gates, but it's ambiguous whether they're capable of leaving.)
* ''Anime/TengenToppaGurrenLagann'' has the human villages deep underground. The planet's surface is overrun with monsters, and humanity has hidden away for so long that most of the people in Kamina's village question whether the surface actually exists.
* In the oneshot manga ''Island'', by Komi Naoshi, the town the main characters live in is surrounded by a huge wall, much like a well. When the islanders turn 14, they are shown the truth- outside their island is nothing but a vast sea. [[spoiler:The islanders believe that all the land in the world sunk and thus all other countries were drowned, making it useless to go outside the island. It turns out that only the island sank, probably because of land subsidence and earthquakes.]]
* Tokyo Jupiter in ''Anime/RahXephon'', encasing Tokyo ([[ExactlyWhatItSaysOnTheTin and looking like Jupiter]]).
* A variety occurs in ''Anime/AngelBeats''. There's no literal wall, but the world around the high school complex just disappears into a thick fog once you travel beyond the hills.
* The "spiritual barrier" around the village in ''Literature/FromTheNewWorld''. The humans inside the barrier are told never to cross it, because the outside world is full of horrific monsters. [[spoiler:They are taught this so that their subconscious telekinesis will only create said monsters outside the barrier. The barrier keeps bad things out ''and'' imprisons the characters, by necessity.]]
* In ''Manga/AttackOnTitan'', the remnants of humanity live inside an area protected by three absolutely massive ring walls. All the lands outside are claimed by man-eating giants that have hunted humanity to near extinction. The plot of the series is kicked off when the walls begin to fail...
** There's also a kind of layered example in how each wall has a quartet of towns situated just outside of it (surrounded by an extended semicircle), serving partially as a waystation in the major gates of the walls, but mostly as a cost reducing factor by baiting the Titans into easily monitored concentrations just outside the towns (the walls there being thinner than the rest). Although there are government incentives to settle such towns, it's offset by needing to live with the constant visual reminder of their enclosure. At least before the first one falls.
* The city of Houryou, in the Kingdom of En, from ''LightNovel/TheTwelveKingdoms'' also has many layers of walls, but in this case, is because of the constant population growth, as more people migrate to En from other kingdoms, the city constantly needs to expand more to accommodate them, and since the walls are needed to protect them from the monsters, they have to constantly be build with the expanding city.
* In ''Anime/YukiYunaIsAHero,'' the setting is the island of Shikoku, which survives as its own country after a deadly virus struck the world hundreds of years ago; they were rescued by the [[WorldTree Shinju-sama]], which is now worshiped as a god. There's a wall around the country; if one goes beyond it, they discover [[spoiler:a hellish landscape filled with [[EldritchAbomination Vertexes]], which is what ''actually'' destroyed the rest of humanity]].
* Meta-example. The universe in which ''Anime/GlassFleet'' takes place is described as a "closed space". The exact details are unclear, but one thing ''is'' made clear: it's ''shrinking'' as more and more of it crosses the event horizon of the Black Cross: a massive black hole.

[[folder:Comic Books]]
* The ComicBook/IncredibleHulk occasionally visited the Keystone Quadrant in his old comic-book series... basically a solar-system (possibly more than one) which was somehow 'walled off' from the rest of the universe, it could only be entered and exited through various types of teleportation. It was basically a SugarBowl without the sugar - populated by funny talking animals and hilariously incompetent Keystone Kops... and caught up in a long war between a MadScientist tortoise and his cybernetically-enhanced Black Bunny Brigade (not to mention a small army of robotic [[MonsterClown Monster Clowns]]), and the heroic Animal Resistance, led by a fast-talking Raccoon space-captain.
* ''ComicBook/SecretWars2015'': [[spoiler:After Dr. Doom cobbles together Battleworld from the remaining fragments of the multiverse, he sets up a wall ''made out of Ben Grimm'' to keep out uncontrollable monsters like the Marvel Zombies, Ultron, and Annihilus.]]
* The Source Wall is a ''metaphysical wall that surrounds all mortal reality'' in the Franchise/{{DCU}}, named after TheSource, Franchise/{{DCU}}'s equivalent of God or the Godhead and introduced in JackKirby's ComicBook/NewGods epic. The Source Wall separates the extant universe from the Franchise/{{DCU}} equivalent of Heaven. Only those godlike beings who can reach the border of reality itself ever encounter it, and its appearance as a wall is indicated to be metaphorical rather than literal. That said, there are powerful cosmic beings embedded in the wall.
** As to the powerful cosmic beings embedded in it: if you try to breach it and fail you wind up [[AndIMustScream eternally trapped but alive]]. There are some powerful creatures who couldn't make it through. By now the wall is so covered with those trapped by it that it looks like a wall made entirely of screaming faces as far as the eye can see.
** In the New 52, the Source Wall surrounds the entire ''multiverse'' and is a literal wall instead of a metaphorical wall. In this case, we have no idea how the geometry works.
* In the "Age of X" ''ComicBook/XMen'' storyline, there's a massive barrier keeping the bad guys out. Kitty phases through it once and finds out [[spoiler:there's nothing beyond it. It turns out the world isn't real, but made by a RealityWarper who is only good enough at this point to make a world that's only so big]].
* In ''ComicBook/{{Fables}}'', a queen was punished for her infidelity to her wizard-king husband by being transformed into a tortoise and having the archipelago on which she was born shrunk and put into a teacup she must constantly balance on her back. We briefly see the inhabitants of the archipelago, who have various myths and semi-scientific theories relating to the colossal white wall (the rim of the cup) surrounding their world. Several of their stories have elements of truth to them, though by and large the people simply accept the wall as a fact of life, and it barely features in their lives beyond having a rite-of-passage where a boy must touch it to become a man.
* The Veil (actually called a Wall in the original) in ''ComicBook/{{WITCH}}'' serves to keep a powerful evil, identified with [[BigBad Phobos]], on the world of Metamoor and keep the universe safe from him, with most people being able to get through the various portals but Phobos being apparently unable to. The Veil becomes unnecessary and is torn down once Phobos is captured and locked in the Tower of Mists.

[[folder:Films -- Animation]]
* ''Disney/TheLittleMermaidIIReturnToTheSea'': To keep her daughter from endangering herself in the sea, Ariel has an enormous wall built around the palace to separate them from it. However, by 12, Melody has learned a way through it: a loose bar on one of the gratings allows her to squeeze through.
* In ''WesternAnimation/TheSecretOfKells'', Abbot Cellach is obsessed with building a wall that will protect his monastery from Viking invasions. [[spoiler:It doesn't work.]] He is very strict with forbidding his charges from going outside, punishing young Brendan harshly when he disobeys.
* In ''WesternAnimation/OverTheHedge'' the animals wake up in the spring to discover a huge hedge is now running through the middle of their forest, but the main plot of the film involves them finding a new housing community on the other side, and begin to use the humans that live there to their advantage to get their food.

[[folder:Films -- Live-Action]]
* The forest containing ''Film/TheVillage'' is closed off from the outside world by a wall. Turns out there's a reason for that.
* The desert that "surrounds" the Maitlands's house in ''Film/{{Beetlejuice}}''. Basically, any ghost who tries to go beyond his/her haunting grounds ends up there until they turn back.
* The walls of Truman's enclosed world in ''Film/TheTrumanShow''.
* The broken bridge in ''Dellamorte Dellamore'', aka ''Film/CemeteryMan''.
* In ''Film/DarkCity'', John Murdoch tries to reach Shell Beach; instead he finds a wall at the edge of the city.
* In the film version of ''Film/AeonFlux'' the survivors of the "industrial virus" (biological apocalypse) have lived in the walled city of Brenga for generations. The outer perimeter of the wall is periodically sprayed with some sort of poison to keep the outside world at bay.
* A (probably apocryphal) story about Creator/HarlanEllison's pitch for the first ''Franchise/StarTrek'' film claims that Ellison met with Paramount executives and provided an outline for an epic story which ended with the crew of the ''Enterprise'' traveling to the edge of the universe, encountering a massive wall there, blasting a hole through it with their phasers, and ''seeing the eye of God staring back at them''. Studio heads, however, were unimpressed, claiming that the premise wasn't "big enough", at which point Ellison stormed out of the meeting.
* In ''Film/TheLastStarfighter'', the entire civilized-good-guys portion of the galaxy is surrounded by an enormous force field called the Frontier. The evil Ko-Dan Armada lies outside the Frontier, but they've found a way to drill through it. (Cue MusicalSting.)
* In ''Film/TheThirteenthFloor'' the world has no physical wall around it but it does have an edge where the simulated nature is visible to the naked eye. People within the simulated world are just programmed to never think about going anywhere near that edge (of course there are exceptions...)
* In ''Film/SexMission'' the survivors of a DepopulationBomb -- only women (reproducing artificially) -- live in a deep mine and are afraid to venture outside, because all their periscope shows is a grey wasteland. [[spoiler:There is a literal wall around the periscope and the surface gate. With very convincing grey wasteland painted on it.]]
* In ''Film/{{Maleficent}}'', the titular character creates a great wall of thorns to keep the humans out of the Moors. King Stephan builds a similar tangle of thorns made of [[ColdIron iron]] in his castle.
* ''Film/RogueOne'' has a forcefield around a planet with a single entry point in orbit. [[spoiler:[[RammingAlwaysWorks Did you know Star Destroyers make good battering rams?]]]]
* ''{{Film/Stardust}}'' is a story about a wall that separates two worlds, one entrenched in magic and the other that is similar to our own.

* In Garth Nix's ''Literature/OldKingdom'' series, a huge, ancient and magic-infused wall separates the mundane, magic-free Ancelstierre (which resembles early 20th-century England) to the South from the MedievalStasis land of the Old Kingdom to the North. Passage across the wall from the Ancelstierre side is tightly regulated, with military checkpoints and watchtowers, though they're also watching for threats, particularly [[TheUndead undead ones]], coming from the Old Kingdom.
* The impenetrable FAYZ Wall which surrounds the area in ''Literature/{{Gone}}''.
* The TropeNamer is a short story by Theodore R. Cogswell in which it separated a magic-dominated half of the world from a science-dominated one.
* In ''Literature/TheSwordOfTruth'' / ''Series/LegendOfTheSeeker'', there is an (almost impenetrable) great barrier around a region called "The Midlands", which is the central geography of the story.
** That barrier is also re-used in ''Naked Empire'' of the same series, to close off a group of people from the rest of the world.
* Creator/IanMcDonald's ''Out on Blue Six''--the city is surrounded by a giant Wall, and the protagonists explore to see what's on the other side. [[spoiler:Turns out--nothing but toxic waste.]]
* In Creator/DamonKnight's ''Hell's Pavement,'' people in Connecticut (200 years in the future) know nothing of the people in New York, who know nothing of the people in Ohio, and so on. They believe people in the other places are literally monstrous and inhuman. (There are walls between zones.) This happened because supermarket chains used brilliant new brainwashing techniques to make people totally loyal to their brands, and the adherents of different brands formed different zones.
* ''Literature/TheHitchhikersGuideToTheGalaxy''
** The planet Krikkit in ''Literature/LifeTheUniverseAndEverything'' was surrounded by a thick fog such that they never saw outside their world. [[spoiler:This was done by the remnants of the supercomputer Hactar, making the Krikkiters into an OmnicidalManiac race once they saw the universe. He did this so they would use the universe-destroying bomb he had invented, thus fulfilling a duty he welshed on long ago and getting rid of his long-standing guilt.]]
** In ''Literature/SoLongAndThanksForAllTheFish'', Wonko the Sane builds an inside-out house he calls "the Asylum" to fence in the rest of the world (he, naturally, lives "outside the Asylum", which is inside the house). He'd decided [[WorldGoneMad the entire world had gone insane]] when he came upon a pack of toothpicks with ''instructions''.
* In the novel ''Literature/HardBoiledWonderlandAndTheEndOfTheWorld'', the End of the World sections take place in a town which has a wall around it, and once you come to the town you can't go outside the wall.
* If you only follow the first book, [[Literature/LandOfOz Oz]] would seem rather like this. The endless deadly desert surrounds Oz on all sides, isolating it rather nicely. Too bad later books place other magical kingdoms on the other side of a desert that seems rather more like a moat. Eventually, all the magic-users in Oz gather their power to put up a wall of invisibility, thus more permanently sealing off Oz.
* There's a short story by Arthur C. Clarke called "The Wall of Darkness" about a planet with a wall that divides it in half. The protagonist spends many years (and most of his wealth) building a staircase to climb the wall to see what's on the other side. [[spoiler:Turns out there is no other side, and the planet is essentially a 3D Möbius strip. The wall was created in the distant past to prevent people from trying to go to the other side, which tends to drive people mad.]]
* The Void in Creator/PeterFHamilton's ''Literature/VoidTrilogy'', arguably.
* A global glacier surrounds the only habitable continent on all of Literature/{{Darkover}}, literally called The Wall Around the World by the inhabitants.
* In ''Literature/TheSingerOfAllSongs'', the order of priestesses known as the Daughters of Taris live surrounded by a giant wall of ice. They are the only people who can use ice magic, so they control who can come in and out.
* The great Agatean Wall in ''Discworld/InterestingTimes'' in more to keep everyone inside, rather than other people out. According to the leaders, there is nothing but ghost and vampire filled wasteland outside it.
* In ''Literature/TheDosadiExperiment'' the whole planet is encased inside the "God Wall" [[DeflectorShields barrier]] as a part of said experiment. Not that it's ''completely'' impassable, but for [[TheMasquerade most people]] inside it is.
* The Land of Elyon, a children's series by Patrick Carman, has walls surrounding the inhabited cities and the roads that link them. The main character finds a way out of the walls, despite the fear of many of the other characters about what is beyond the walls.
* The Green Wall in Yevgeni Zamyatin's ''Literature/{{We}}'', separating the civilization of the One State from the forests around it, which in turn separate them from the rest of the world. We are given few and conflicting clues as to what actually may exist beyond the forest.
* Creator/TedChiang's ''Tower of Babylon'' is a speculative fiction short story where it's more of a ceiling [[spoiler:or floor]]. The vault of heaven is a literal stone roof to the universe, and the Babylonians have built a tower to talk to God, who they believe resides above it. [[spoiler:One of them makes it, only to emerge from a cavern deep in the Earth, back where he started--somewhat similar to the Clarke example above, the world loops back on itself.]] In another story, ''Exhalation'', the narrator mentions how he has "journeyed all the way to the edge of the world, and seen the solid chromium wall that extends from the ground up into the infinite sky."
* Marlen Haushofer's "The Wall" is about a woman one day waking up in a mountain valley with the whole valley suddenly surrounded by an invisible, impenetrable wall. With all life outside the wall apparently dead, the book deals with her trying to survive inside the valley. Wondering if she is the last human alive, she speculates about the origin of the wall, [[spoiler:which in the end is never revealed. She often thinks about trying to leave the valley, but can't bring herself to risk it. What happens to her in the end is left open to the reader.]]
* Creator/JimButcher's ''Literature/TheCinderSpires'' series has the Mesosphere, a thick layer of mist that covers the surface of the world, and is inhabited by some very large, very ''hungry'' things, and the titular Spires themselves; Two miles wide, tall enough to reach above the Mesosphere, and each populated by a nation of people who are, more often than not, overcome by agoraphobia if they ever actually go outside.
* ''Literature/TheReynardCycle'': Deconstructed by the Muraille, a series of fortresses connected by a wall meant to serve as the eastern border of Arcasia. Unfortunately, the finished product was AwesomeButImpractical: It could never be fully manned, and has been breached so many times that the whole thing has been abandoned.
* ''Literature/PerryRhodan'' uses this on a number of occasions (including a 'wall' around the entire ''Milky Way Galaxy'' that the protagonists had to deal with after losing a few hundred years in an unexpected stasis field while outside, once). There's also a more literal example in Wardall, a tide-locked planet with a wall running around its entire circumference following the terminator. The planet's former natives apparently lived ''inside'' said wall rather than on either side of it, not surprising considering the conditions there; by the time the issue set on the world opens, though, its only inhabitants are the surviving crew members of a crashed pirate vessel and their descendants.
* The wall separating Experiment House property from Narnia in ''Literature/TheSilverChair.''
* A literal example is the spherical Walls of the World from Creator/JRRTolkien's legendarium, which are only specifically described in ''Literature/TheHistoryOfMiddleEarth'' although their existence is implied in ''Literature/TheSilmarillion''. The walls separate the world from the empty void of the Outer Dark, and are only pierced by a single Door of Night, created by the Valar to thrust [[BigBad Morgoth]] out until TheEndOfTheWorldAsWeKnowIt.
* A large portion of the plot in Orson Scott Card's ''Literature/{{Pathfinder}}'' revolves around one of these. It's revealed decently early on that there are actually 19 "worlds" with Walls.
* In ''Literature/TheLegendsOfEthshar'', the world of Ethshar is a FlatWorld, being the end-cap of a cylinder. The edge of the end-cap is marked by a "noxious yellow gas".
* The wall (or "Barrier") in Lee Arthur Chane's ''Magebane'' was created long ago by mages as a defense against a [[WhatMeasureIsANonSuper commoner uprising]]. It's assumed that it will last for another two hundred years. [[TheMagicGoesAway This is a bit of an overestimate]].
* There aren't any literal walls in ''Literature/TheCityOfEmber'', but there might as well be -- the only light comes from the city, as does all of the food and other necessities, making it impossible to leave. Nobody in the city knows what might exist outside of it, if there's anything there at all. [[spoiler:It turns out that the entire city is actually underground. The original builders included instructions for leaving the city to be used after a certain amount of time had passed, but they were lost and forgotten before they could be used, leaving the citizens trapped in a city with dwindling food and power supplies, and no way of knowing that escape was necessary or possible.]]
* Natives of the planet Lookout in Jack [=McDevitt=]'s "Omega" live on an isthmus (narrow strip between continents -- like Panama), with basically-impassable terrain on both ends. They pretty much believe they're on an island amidst an infinity of ocean.
* The prologue to the ''Forbidden Borders'' series by Michael Gear tells how SufficientlyAdvancedAliens [[ScaryDogmaticAliens tried to teach humans "reasonable" non-violent behaviour]] since they considered extermination unethical. They trapped a score of human colonies inside "gravitic bottles", which humans dubbed Forbidden Borders, and [[ColonyDrop dropped an asteroid]] on Earth. First they tried to guide humans via a telepathic supercomputer. They managed to slow technological progress and make them forget Earth, but humans contacting the computer ended up forming a cult and keeping its knowledge to themselves. When the aliens tried to force the cult to share their knowledge, the cult just abandoned the computer. As of the series start the aliens were expecting humans to exterminate themselves in the upcoming war of attrition.
* The planet Saraksh in ''Literature/PrisonersOfPower'' by the Creator/StrugatskyBrothers has an atmosphere with very high refraction, which leads its inhabitants to believe that they live not on the outer surface of the globe, but on the inner one. They can see the surface around them curving upward, [[AlienSky as far as dense low clouds allow them to see]]. The idea that they live on an outer surface ("mas-saraksh", "inside-out world") is well known, damned by all religions, commonly used [[ForeignCussWord as an expletive]], but gives surprisingly accurate results for plotting trajectories of [=ICBMs=]. Only the insane believe in existence of other worlds, and a crash-landed alien is considered a mutant.
* ''Literature/{{Incarceron}}'', being a giant prison, is surrounded by massive steel walls.
* ''Literature/{{Oathbringer}}'' (third book of ''Literature/TheStormlightArchive''): Shows up as a myth of people living in a land of shadows surrounded by a wall to keep the monsters out, only for one girl to climb the wall and bring back light, and in the process she discovers the wall is to keep the monsters in. [[spoiler:This appears to be a mythologized account of human settlement in Shinovar, which completely lacks stormlight, and their eventual conquest of the world]].
* Several stories in the world of ElricOfMelnibone show that its world is surrounded by a WorldOfChaos that is inhospitable to human life. One major guardian of the walls is [[BarrierMaiden the lawful good sorceress Myshella]].

[[folder:Live-Action TV]]
* ''Series/BlackMirror'': The episode "[[Recap/BlackMirrorHangTheDJ Hang the DJ]]" has the main characters living in a world that they know to be walled off, referred to as The System. The climax involves them attempting to escape The System by climbing over the wall.
* ''Series/GameOfThrones'': Characters refer to the Wall as "the edge of the world." The Wall itself has startling parallels with Hadrian's Wall, a huge, 80 mile long barrier stretching across the top of England which was began in AD 122 and built to protect Roman Britain from Scottish invasion. Unsurprisingly, George R.R. Martin has stated that a visit to Hadrian's Wall was his inspiration.
* ''Series/StarTrekTheOriginalSeries'':
** The [[TwoDSpace barrier around]] [[SciFiWritersHaveNoSenseOfScale the galaxy]] in the episode "Where No Man Has Gone Before".
** Another old series episode, "For the World Is Hollow and I Have Touched the Sky", where the world is a hollow asteroid.
* ''Series/DoctorWho'':
** In the story "Inferno", the Doctor pushes through a barrier in time and ends up in a MirrorUniverse.
** Also used in the ''[[Magazine/DoctorWhoMagazine DWM]]'' comics, most notably in "Oblivion".
* On ''Series/ThePrisoner'', the mysterious Village is surrounded by unclimbable mountains to the north, and the sea to the south. On several occasions, the eponymous Prisoner attempts to escape by boat, but he always ends up getting caught.
* In the fourth season of ''Series/{{Heroes}}'', Sylar is imprisoned in a section of abandoned Manhattan with a wall around it. Since this is a psychic prison imposed on him by a telepath, there is actually NO "outside".
* In the ''Series/TheXFiles'' episode "The Lost Art of Forehead Sweat", an alien declares that his people have decided to wall off Earth's solar system to prevent further contact with humans (with a TheReasonYouSuckSpeech [[TakeThat parodying]] Creator/DonaldTrump's remarks about securing the US-Mexico border).

* Music/PinkFloyd's ''Music/TheWall'', which isolates the protagonist from... the world in general, but especially his fans.
* The second act of ''Music/RaziasShadow'' starts after the world was split into the light and dark.

[[folder:Myths & Religion]]
* Jericho, from ''Literature/TheBible'', is now synonymous with its absurdly strong fortifications. Tends to happen when it takes ''God Himself'' to bring them down.
** There is also reference to the sky being a firmament, a literal wall around the entire world. This is slightly different than the usual application of this trope, as there is pretty much nothing outside of the area enclosed by the firmament, which exists to hold back the waters that are the source of rain. Although the Book of Isaiah does describe Yahweh as having his throne on top of the firmament.
* A pre-Islamic Turkic myth has the Turkic people fleeing into a valley surrounded by mountains of iron to survive an onslaught. Their point of entry collapses, effectively sealing them from their enemies and letting them stay there for generations. When they decide to leave, they do so by ''melting'' the iron mountain.
* In Literature/TheQuran itself, there's a story of [[https://en.wikipedia.org/wiki/Dhul-Qarnayn Dhul-Qarnayn]] (Arabic for "The Two-Horned"[[note]]possibly alluding to a horned helmet that he wore?[[/note]]), who [[https://en.wikipedia.org/wiki/Dhul-Qarnayn#People_identified_with_Dhul-Qarnayn may or may not be the same as one of several historical figures]] (among whom are Alexander the Great and Cyrus the Great), being asked to protect a people from their enemy, the Ya'juj and the Ma'juj (Arabic names of Gog and Magog, but as peoples instead of individuals). He does so by building an exceedingly tall wall entirely made of iron, with a massive iron gate that's difficult to open.
** There's also a 'wall' (more metaphorical than literal) between this world and the realm of the dead, that absolutely no one can pass. The wall is the reason why there are few (if any) ghost stories in the Islamic world.

* Some modern believers in a flat Earth (yes, there're people who believe it) say the world is encircled by a ''huge'' (150' (46m) tall) wall of ice located in Antarctica[[note]]See [[http://rationalwiki.org/wiki/File:Flat_earth.png for example this map]] to understand what it means[[/note]], with thousands of {{Super Soldier}}s taking care nobody sees that barrier. [[http://wiki.tfes.org/index.php?title=The_Ice_Wall Quoting]] [[TheWikiRule from their wiki]] in what refers to what exists beyond said wall:
-->Beyond the 150 foot Ice Wall is anyone's guess. How far the ice extends; how it terminates; and what exists beyond it, are questions to which no present human experience can reply. All we at present know is, that snow and hail, howling winds, and indescribable storms and hurricanes prevail; and that in every direction "human ingress is barred by unsealed escarpments of perpetual ice," extending farther than eye or telescope can penetrate, and becoming lost in gloom and darkness. Some hold that the tundra of ice and snow stretches forever eternally.

[[folder:Tabletop Games]]
* The borders between the physical realm and the spirit worlds in the ''TabletopGame/OldWorldOfDarkness'' RPG line (the Gauntlet and the Shroud) qualify. Most humans have no idea that the spirit realms are real.
** The Gauntlet still stands in the TabletopGame/NewWorldOfDarkness, cutting off the Shadow from the material. There's also the Abyss, which severs the Supernal from the Fallen.
** The NWOD is full of these, and [[HoldTheLine generally for the better]]. The Gauntlet is the border between the real world and the spirit world. The Hedge is the border between the real world and [[TabletopGame/ChangelingTheLost Arcadia]]. It takes the form of a thick thorny bush that hurts the soul of anyone passing through it. There's also an unnamed wall that prevents interaction between the real world and Inferno.
* TabletopGame/DungeonsAndDragons, [[{{Troperiffic}} as always]]:
** The Misty Border in the ''TabletopGame/{{Ravenloft}}'' setting cuts it off from the rest of the multiverse. You can check in, but you never check out. Darklords can do this at will (with a few thematically-appropriate exceptions) to isolate their own domains.
*** The town of Barovia has its own permanent version of its domain's closed border; only the Vistani know how to make a secret antidote that allows safe passage.
** ''TabletopGame/{{Spelljammer}}'' has a borderline case: crystal shells. Oh, it can have many thousands of portals... spread over the whole surface of a ''star system'', that is. It's not easy to find one without knowing where it is, and they don't always stand still forever. Thus the proper magic is the best way to locate a portal or even open a temporary one -- for those who have it.
* The Weirding Wall in ''TabletopGame/{{Nobilis}}'' which encloses the whole universe.
* ''TabletopGame/{{Paranoia}}'' is set in Alpha Complex, a domed city. The existence of "Outdoors Sector" is acknowledged, but information about it is limited, especially at low security clearances.
* ''TabletopGame/{{Exalted}}'': Faxai-on-the-Caul, the only [[TheEmpire Realm]] city on the Lunar-controlled island of the Caul, is surrounded by massive walls; not only are they a major reason the city hasn't fallen, they're also partially why the Realm wants to keep a presence there (as legends state they were made by a venerated figure). The lands beyond are largely unknown.
* Partially averted with the magical barriers that divide the setting of ''TabletopGame/AnimaBeyondFantasy'' in three smaller, spherical ones plus a bunch of much smaller territories that did not get included in them. Depending on someone's location, those barriers take different forms - from a large, perpetual tempest that allows circumnavigation of the (sub)world in the case of the human territories to terrain that repeats again and again in the case of some of those separated territories.

[[folder:Video Games]]
* ''VideoGame/CustomRobo'' (the Gamecube version) has the humans live inside a domed city that isolates them from the post-apocalyptic world. The outside world is kept secret except to a select few. But [[spoiler:when you beat Rahu III, the final boss, it is revealed to everyone]].
* In ''VideoGame/{{Grandia}}'', an entire continent was divided by an enormous wall about a mile high. No one ever tried to explain ''why''.
** Could have something to do with [[EldritchAbomination Gaia]] [[TakenForGranite killing]] [[FateWorseThanDeath almost]] [[RealityWarper everything]] in its path, as it's only encountered on that side of the wall until it got on an airship.
** ''VideoGame/GrandiaII'' had something similar, a huge nigh-uncrossable canyon, though its existence was explained: it was basically caused by God crashing into the earth.
* In ''VideoGame/{{Wild ARMs 4}}'', your first indication that Ciel is not a typical RPG hamlet is when fighter craft shatter the barrier surrounding it that was disguised as sky. The outside world is quite a bit different.
* ''VideoGame/CityOfHeroes'' has the War Walls, [[JustifiedTrope justified]] as barrier against alien invasion, but really there as a level separation.
* Palm Brinks in ''VideoGame/DarkCloud 2'' was [[CityInABottle sealed off from the rest of the world]] via a titanic wall, far too tall to scale. This was done by the Mayor, to protect the citizens from the incredible devastation taking place in the outside world --but now that the land is healing (and with the heroes having escaped via an underground sewer/aqueduct,) many of Palm Brink's inhabitants dream of exploring and building new cities.
* ''VideoGame/StarControl 2'' has slave shields -- barriers around homeworlds of defeated races who don't want to fight on Ur-Quan side.
* ''Franchise/TheLegendOfZelda'' uses the trope in varying degrees:
** ''VideoGame/TheLegendOfZeldaTheWindWaker'': The Great Sea has no physical barrier to keep you from leaving the map. However, your boat tells you that it's dangerous to leave and turns you around.
** ''VideoGame/TheLegendOfZeldaSkywardSword'' has an impenetrable cloud cover that separates the residents of Skyloft from the surface. As far as the people of Skyloft are concerned, the "surface" is a mythical place, rumored to be filled with monsters.
** In ''VideoGame/TheLegendOfZeldaALinkToThePast'', Hyrule is a valley bordered on all sides by impassable mountains and a thick forest on the Northwest. No one knows or even speculates on what's beyond. Considering that it's landlocked, [[FridgeLogic it makes you wonder]] where Link boarded the ship from the intro to ''VideoGame/TheLegendOfZeldaLinksAwakening''. [[spoiler:He boarded from the coast of [[VideoGame/TheLegendOfZeldaOracleGames Labrynna or Holodrum]], where he had been teleported]]
** Speaking of which, Koholint Island in ''VideoGame/TheLegendOfZeldaLinksAwakening'' is an island in a vast ocean. Its inhabitants have not attempted to build any sailing vessel more advanced than a rivergoing raft, and most express surprise and disbelief at the notion that there ''is'' a world outside their island. [[spoiler:This is because the island and everyone and everything in it exist only in the dream of the Wind Fish.]]
** ''VideoGame/TheLegendOfZeldaBreathOfTheWild'' uses a mixture of ''A Link to the Past'' and ''The Wind Waker'' in terms of natural barriers. The north and and west portions of Hyrule are cut off by a massive gorge, the southwest has an expansive desert, and the south and east are nothing but the sea. The gorge is too wide to fully cross and too deep to go down safely, the desert kicks up an impassible sandstorm if you try to go any further, and venturing beyond the sea just greets you with an invisible wall. Trying to climb cliffs near these barriers will have the game force Link to dislodge from the wall to prevent him from climbing. What makes it stranger is the world map does show more landmass beyond the desert and chasms, but no one in game ever mentions it.
* Gensokyo, the setting of the ''VideoGame/{{Touhou}}'' games, is walled off from the Outside World by the Great Hakurei Barrier [[FantasticNatureReserve to preserve]] {{Youkai}}, though people and objects occasionally slip through (particularly things the outside world has stopped believing in).
* There's no actual wall on Hillys in ''VideoGame/BeyondGoodAndEvil'', but if the player strays too close to the edge of the map, a series of pillars will rise up out of the water and warn the player that they're leaving territorial waters. Trying to get past them will just lead to them shooting non-lethal lasers at the player's vehicle to turn it around.
* ''VideoGame/{{Lusternia}}'' is comprised of the Basin of Life, which is entirely isolated from the rest of the world by mountains. Nobody can get out, but there have been cases where denizens have come in from/gone out to some place on the outside.
* In ''VideoGame/{{Fallout 3}}'', Vault 101 was intended to never open its door. The line is, "No one ever enters, and no one ever leaves." [[spoiler:[[SubvertedTrope Neither are true]]: your dad is from Rivet City, and you and he both leave.]]
* The ''VideoGame/{{Hexen}} II'' [[AllThereInTheManual manual]] states that the universe is surrounded by a crystal barrier, beyond which there is a darkness inhabited by demons. The Serpent Riders are merely the three who slipped through a tiny hole which was sealed almost immediately.
* ''VideoGame/SkiesOfArcadia'': The western half of the planet is surrounded by a giant maelstrom with the Empire in the eye of the storm. Survivors claim there are weird monsters in there, and most sailors believe the population of said monsters is endless, but there's an Asian-themed empire on the other side.
* In ''VideoGame/TalesOfGraces'', the entire world of Ephinea is surrounded by the Aquasphere, an enormous bubble of water. The only thing that can been seen through the Aquasphere is Foselos, a ring of...actually, no one on Ephinea knows. [[spoiler:Foselos keeps the Aquasphere stable, and the reason there is an Aquasphere in the first place is to keep the people of Ephinea from seeing [[GhostPlanet Fodra.]]]] Notably, the trope is played with; while the Turtelz are somewhat curious as to what, exactly, Foselos is, only some people in the Amarcian Enclave seem to care about the Aquasphere, and it takes [[DitzyGenius Pascal]] messing around with a computer from the old Amarcian Enclave to even find the 'name' of the Aquasphere.
* ''VideoGame/TheAmazingFrog'' features the town of Swindon, which is surrounded on all sides by an enormous wall that's nearly impossible to pass over, unless you either jump high enough or find the secret hold in the wall.
* Exploring the OverworldNotToScale in ''VideoGame/PhantasyStarIII'' soon gets the party to a featureless grey wall that looks quite different from the plains and mountain ranges and does not seem to have any openings. [[spoiler:The truth is revealed about 2/3 into the game, near the end of the second generation: The worlds are artificial, and actually part of a giant spaceship. The 'caves' you have been using so far to get from one world to the other are its maintenance tubes.]]
* The [[DarkWorld Underground]] from ''VideoGame/{{UNDERTALE}}'' is the home of the race of 'monsters'. After a war with humanity, humans [[HumansAreTheRealMonsters forced them into the Underground]] and created [[SomeKindOfForceField a magical barrier]] preventing anyone leaving (although people can still fall ''in''; for example, the {{protagonist}}, who becomes TrappedInAnotherWorld). It can be broken by [[PlotCoupon seven human souls]] or passed but left unbroken by one who possesses both a human soul and a monster soul. PlayedForDrama: an OverpopulationCrisis in the restricted space of the Underground creates social problems in the monster society. Plus, they're living entirely off whatever humans dump into the Underground. That includes what they're eating.
* The world of ''VideoGame/{{Xenoblade}}'' consists of two behemoths standing in an endless sea. If the characters reach the beaches at the bottom of the world and step into the sea, they lose HP rapidly until collapsing and winding up back on shore.
* The land in ''VideoGame/XenobladeChroniclesX'' is made up of five linked continents, each with unique ecosystems, surrounded by an endless ocean. The player is able to swim or sail out onto the ocean but as soon as the land is no longer in view, the game produces an invisible wall and throws up a message that you cannot continue on.
* Everything related to ''Franchise/DragonAge'' is set on a single continent named Thedas, and although the franchise's lore stretches back for several thousand years, almost nothing is known of the world around Thedas. The continent is walled in by massive mountain ranges to the west, impenetrable jungles to the north, frozen wastelands to the south and endless oceans to the east. Many have tried to explore these regions over the millennia, but scarcely anybody has ever returned, and those that did can't tell much because they didn't get far enough to uncover anything of note. As far as the average Thedosian is concernced, there's nothing beyond Thedas but rumors, legends and death.
* The 2013 ''[[VideoGame/TombRaider2013 Tomb Raider]]'' reboot takes place in the Pacific on the lost island kingdom of Yamatai, an EldritchLocation surrounded by neverending storms that destroy any vessel that tries to approach or leave the place. No wonder the game's ArcWords are "no-one leaves". It's your job to help Lara find a way to defy these words, dissipate the storms and get the hell off the island.

[[folder:Web Comics]]
* The area known as The States in ''Webcomic/WhiteNoise'' is surrounded by a gigantic wall and poison gas filled moat. No one is allowed in or out except for bounty hunters, and residents hate and fear those who live beyond it.
* In ''Webcomic/SluggyFreelance'' the "Punyverse" turned out to be surrounded by a giant solid sphere, the inhabitants mostly didn't know that and thought it was an endless void inhabited by "void ghosts" that occasionally attacked (it was really wild shots reflecting off the sphere). Also [[spoiler:their entire universe was artificial.]]
* A massive mountain range in ''Webcomic/LeifAndThorn'' between Sønheim and Ceannis, keeping their magic systems separate. The Sønheim embassy in Ceannis [[http://leifandthorn.com/comic/homecoming-524/ has a big wall around it]] to replicate the effect.

[[folder:Web Original]]
* Our whole ''universe'' in ''Literature/FineStructure'' is 'walled'. Nothing gets in or out. [[spoiler:It's actually a prison designed to keep Oul inside.]]

[[folder:Western Animation]]
* ''WesternAnimation/TheSimpsons''
** The glass dome enclosing Springfield in TheMovie.
** And the wall made of garbage separating Springfield from New Springfield.
* In ''WesternAnimation/{{Futurama}}'', the Planet Express crew visits the Edge of the Universe, which has a convenient viewing platform. They are able to look through binoculars at the Universe Next Door, (which is apparently cowboy-themed).
-->'''Fry:''' Wow. So there's an infinite number of parallel universes?\\
'''Professor Farnsworth:''' No, just the two.
* ''WesternAnimation/SouthPark'':
** In the episode "Pinewood Derby", [[spoiler:Earth and the Moon are sealed off by a cube-shaped force field after the humans fail the Space Cash Test]].
** In the episode ''Child Abduction is Not Funny'', the paranoid parents in South Park had Mr. Lu Kim build a huge wall around the town to keep kidnappers out. It was ordered to be demolished again at the end of the episode [[ShaggyDogStory after spending the entire episode protecting it from Mongol invaders]].
-->'''Mr. Lu Kim''': Aw, you'd better not say what I think you're gonna say.
-->'''Mayor [=McDaniels=]''': Mr. Lu Kim, tear down this wall!
-->'''Mr. Lu Kim''': Oh, God! I hate this whole shitty!
* The ''WesternAnimation/{{Duckman}}'' episode ''Exile in Guyville'' had a wall being built down the middle of America, dividing the sexes with Women on the East and Men on the West.
* Ba Sing Se, the Earth Kingdom capital in ''WesternAnimation/AvatarTheLastAirbender'', is surrounded by two giant walls. People within the city are generally [[MindControlConspiracy encouraged]] not to even ''think'' about the world outside the walls.
* ''WesternAnimation/PhineasAndFerb'': in "Escape from Phineas Tower", the titular tower traps Phineas and Ferb and their friends in a dome. To escape, they make the tower realize they have friends in multiple places, causing the tower to encase larger and larger areas into its dome, until eventually the dome ends up surrounding the entire Milky Way galaxy.
* ''WesternAnimation/TheFairlyOddParents'': in "Love Struck", Timmy wishes for the world's population to be divided by gender, causing the Earth to be split up in a men's half and a woman's half, separated by a large wall circumnavigating the Earth at the poles.
* ''WesternAnimation/HeManAndTheMastersOfTheUniverse2002'' : The Mystic Wall separates the Light and Dark hemispheres of Eternia. For a time its utterly unbreachable and, as far as inhabitants on either side are concerned, a literal wall around their portion of the world. Right up until current events are kicked off in the series, when Skeletor breaks it down.