Ringworld.

The ' (1970–2004), by science fiction author Larry Niven, is a part of his Known Space set of stories. Its backdrop is the Ringworld, a giant artifact 600 million miles in circumference around a sun. The series is composed of four standalone science fiction novels, the original award-winning book and its three subsequent sequels: 1970: Ringworld 1980: The Ringworld Engineers 1996: The Ringworld Throne 2004: Ringworld's Children The core series was developed with three side series of prequels set in the same Ringworld universe, and written in collaboration: 1988–2009: Man-Kzin Wars (by various edited by Niven) 2007–2010: Fleet of Worlds (by Niven and Edward M. Lerner) 2010-2011: Juggler of Worlds (by Niven and Edward M. Lerner)