Ringworld series
The Ringworld series is a series of science fiction novels written by American author Larry Niven. It is part of his Known Space set of stories. Its backdrop is the Ringworld, a giant artifact 600 million miles in circumference around a star. The series is composed of five standalone science fiction novels, the original award-winning book and its four sequels: "Fate of Worlds" is also a sequel to the four books of the Fleet of Worlds series, set in the same "Known Space" universe and all written by Niven and Edward M. Lerner: