The Citadel Is a Spaceship That's Been Permanently Docked

This is a spaceship that's been permanently docked. We don't know if the other things called towers here are also docked spaceships or not, or if this is unique to their guild. It could be that much of the architecture of NASA's repurposed stuff. Also, he mentioned some lights that we're supposed to have burned forever though some of them have gone out. This gives us a sense of the time of from when this chamber was used for its primary purpose.