From the introduction:
The city of Nexus was long ago built by the wizard Parthum, carved into a set of two massive stone disks, they were enchanted to hover far above the lands below. The rings would slowly turn as the city made it’s way across the world, traveling to designated teleportation circles that those on the lands below can use to access the city. However this was before the veiled plague occurred which left the city abandoned.
The streets were much like those you’d see in any city apart from the walkways that allow access within the inner disks. Taverns and stores of all kinds were very common, dealing easily with the influx of visitors as the city travels from place to place. Purchasing exotic magical goods or rare tomes and even trying strange foreign foods was even possible in Nexus. It also housed many temples for the worship of the gods and had accommodation in surplus.