The ship's interior is a hollow cylinder with an "ocean" that wraps around its center. Artificial Gravity:

, is your holy grail. Often overshadowed by his other giant, 2001: A Space Odyssey

The most haunting aspect of the book is the aliens themselves—or rather, the lack of them. The crew finds "biots" (biological robots) and sprawling empty cities, but the creators of Rama remain a complete enigma. Quick Facts Rendezvous with Rama by Arthur C. Clarke - Fantasy Faction