Ringworld

Ringworld is a Hugo and Nebula award-winning 1970 science fiction novel by Larry Niven, set in his Known Space universe. The work is considered one of the classics of science fiction literature. It is followed by three sequels, and it ties into numerous other books set in Known Space. In the year 2855, four adventurers (two humans and two aliens) explore a mysterious "ringworld": an enormous, artificial, ring-shaped structure that surrounds a star. The story is set in an extremely technologically advanced universe, where instant teleportation and nigh-indestructible spacecraft hull are commonplace. Nessus is a Pierson's Puppeteer, a species with the most advanced technology in Known Space. Being descended from herbivorous herd animals, their morality is more-or-less based on cowardice: the ruling class is known as they-who-lead-from-behind, and the supreme leader is called the Hindmost. Puppeteers who display any signs of bravery are considered insane by their peers, and in fact are... full article at wikipedia