Covenant of Heroes
The city of Covenant is a completely self-sufficient, artificially constructed living environment adrift in the Astral Sea. It was built under mysterious circumstances on a dying world shortly before that plane entirely disintegrated. The only survivors to the incident were a few hundred individuals on the extra-planar space that grew to become Covenant. Over a period of centuries, the city was expanded under the government of the “Founders”, several individual entities of extreme power, and now comfortably supports numerous races of diverse origins. The city contains its own power source, and is capable of vaguely controlled astral drift, allowing it to move towards or away from target destinations over a long period of time.