Nobody knows who built the Concourse, or why it exists.
The structure is a sealed artificial habitat suspended somewhere beyond ordinary space. Its outer walls are lined with countless sealed entrances, each marked with strange identification codes and protected by unknown access systems. Some appear recently used, others have not been opened for centuries.
At the center lies the only place that resembles civilization: a small marketplace surrounding an impossible yellow phone box. The merchants here are travelers, scavengers, and survivors from countless worlds. They trade in repairs, unusual technology, forgotten artifacts, and things that may not have names in any known language.
The four residential blocks provide a strange kind of refuge. Each occupant receives a private living space that seems tailored to their needs, though it is unclear how the Concourse knows what those needs are. The rooms are functional, clean, and perfectly maintained, but the feeling remains that the place is not offering hospitality. It is maintaining its inhabitants.
The Concourse has no visible entrance, no visible exit, and no clear purpose. The only certainty is that people arrive here. The question of whether anyone can leave remains unanswered.