Disc shaped cities that float above both land and sea. Generally inhabited only by Aerani or other space-adapted post-humans.
The Kordath Confederation unites most of the sky cities. It is a loose political affiliation left over from centuries ago when the Aerani were on the front lines of an invasion by hostile Returners. Now the confederation exists mainly to keep the peace between the aeropoleis and maintain some sort of cultural connection. Several sky cities have gone rogue, though, and some have even been taken by Returners, who often turn to piracy and kidnapping to supply their needs. See Aerani entry for more info.