Most prisons have walls and guards. This one is open to the air. In fact, there's open air below it as well. The only way out is through the door or by flying. May be on top of a tower, but that's not necessarily the case. Obviously, this tends to be an example of The Alcatraz, as most settings rarely have people capable of unpowered flight. It's rarely a Tailor-Made Prison, simply because it's a rather generic way of containing people who can't fly. Of course, it is used for prisoners you don't have much need for, as nothing prevents them from easily "escaping". The captors may even count on it.
Note that the key aspect is an easily reachable drop, or unlocked airlock IN SPACE!. If reaching the fatal drop requires what would be a major breakout attempt on the ground, it's not an example of this trope. If you're not quite sure, ask yourself if it would be remotely secure on the ground. If so, it's not an example.
- In Thorgal there is "mouth of the Sun", though it is more a death penalty than a prison. The victims are taken (via a net on ropes) to a small cave in the face of the cliff. Not only do they have no way out, short of jumping to their deaths but the whole thing is located in the desert and the cave is facing south and not nearly deep enough to provide shade... even if it wasn't filled with mirror-like crystals.
- Lucky Luke: "Tortillas for the Daltons" has Joe escape from Luke onto a mesa... only to find that he's trapped on maybe four square feet of dirt. When Luke suggests he come back in a year or so, Joe quickly surrenders.
- Judge Dredd has one "prison" that's simply a raised platform above a constantly busy superhighway. Any crooks that tried to escape would be pulverized by traffic.
- In Time Bandits, after Evil takes the map, he locks the Bandits in a cage hung above a huge chasm.
- From the movie First Knight, as Guinevere is led across a hanging bridge to a small ledge over a bottomless pit...
Maligant: This is called an oubliette. That's French for "a place of forgetting." Your quarters, My Lady. No gates, no bars, no locks. Just walls of air.
- The Trope Namer is A Song of Ice and Fire, where the Eyrie's cells have slightly sloped floors and carved into a mountain, with one side open to the sky. If prisoners happen to accidentally fall out before their trial, so much the better. Even those who don't eventually go mad from the constant fear of falling and leap to their deaths. It's also mentioned that their floors don't all slope at the same degree — some have gentler slopes and some steeper, and unruly prisoners are kept in line with the threat of being moved to a more steeply sloping sky cell.
- In The Lord of the Rings, Gandalf is confined onto the flat top of the tower of Orthanc until he is rescued by a giant eagle.
- In Jim Butcher's Codex Alera, some Alerans are confined on top of a building by someone who doesn't believe in furycrafting. The windcrafter in the group is able to fly away and report back without difficulty.
- Rapunzel: Rapunzel's tower has windows that a human can climb through, but the room is so high up that the only way to get up there is by climbing up her own long hair.
- Flashman on the March: Flashman is forced through a trapdoor into a cage hanging above an abyss. Later he forces an enemy in there and shuts the trapdoor on him; on opening it later on, he finds the rope holding the cage has broken, sending the occupant plummeting to his death.
- The citizens of Columbia in Bioshock Infinite have done this to themselves out of extreme xenophobia. Booker is infiltrating it to get what may be the only sane person left out.
- The Aerial Prison in Final Fantasy Crystal Chronicles: The Crystal Bearers.
- An Ard Skellig island in The Witcher 3: Wild Hunt has prison cells clearly inspired by the sky cells from Game of Thrones, as proved by the corpse of a Tyrion lookalike and some lines of dialogue taken from the show.
- Durgesh Prison from Far Cry 4 has a few of these. Ajay gets stuck in one and escapes by assembling a makeshift grappling hook.
- Avatar: The Last Airbender: The Earthbender prison is built far out at sea with only a few token handrails, ensuring the prisoners have no contact with dirt to fight with.
- The Legend of Korra: While Zaheer's prison has walls, it's built on a remote mountaintop and still has guards. Every precaution was taken, but no one (including Zaheer) could have predicted that he'd gain airbending abilities that allowed him to quickly escape the mountain.
- The second season of Loonatics Unleashed has many dangerous superpowered criminals moved from deep subterranean burrows to a prison satellite in orbit above the stratosphere of Acmetropolis. Many of the Loonatics' Rogues Gallery are housed in the satellite, including Massive, Otto the Odd and Electro J. Fudd.