Ringworld is a 1970 science fiction novel by Larry Niven, set in his Known Space universe and considered a classic of science fiction literature. Niven later added four sequels and four prequels. (The Fleet of Worlds series, co-written with Edward M. Lerner provides the four prequels as well as Fate of Worlds, the final sequel.) These books tie into numerous other books set in Known Space. Ringworld won the Nebula Award in 1970, as well as both the Hugo Award and Locus Award in 1971.