The Swallowed City is a former Prime city (or part of one, at least), having since been pulled into the Astral upon the formation of a new conduit. Set on not letting this event be the end of their home, the resourceful citizens of the city set to work binding the chunks of land on which the various buildings still stood together, with whatever materials they happened to have handy. Now, the city drifts through the Astral, consisting of dozens of separate islands each with a single building, each tethered to the other with rope, chain, and other such items.
The center of the Swallowed City, Kinnifar Keep, is also the ruling center of the city, and it's from this castle that the city's tethers largely radiate out from. The city's high-up, Lord Alfred Kinnifar, has ruled the town since it was first pulled into the astral; he's the glue that holds the city together, and the backbone of the city's morale.