1. Exterior of the urban asteroid during heavy space traffic, showing Saturn ring-shaped cooling fin and sunlight focusing mirror.
2. Caverns between 0-10km below the surface. Centrifugal habitats cling between two boulders, while city sprawls overhead. Heat pipes in distance.
3. View into the central cavern, or 'gravity balloon'. About 10km below the surface, the weight of rock in low gravity pressurizes a vast sphere of air.
4. Inside an individual urban "spindistrict" as seen in 2) and 3).



