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 slowly turn as the city makes it’s way across the world, traveling to designated teleportation circles that those on the lands below can use to access the city.
The streets are 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 are 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 is possible in Nexus. It also houses many temples for the worship of the gods and accommodation in surplus.