Ringworld
Louis Wu, a Kzinti diplomat Speaker-to-Animals and the genetically lucky human Teela Brown are recruited by a member of a long-lost race to investigate an immense artifact outside Known Space: the Ringworld.
The Ringworld is an enormous artificial world built in the shape of a ring, with gravity generated by the ring's spin. During their investigations of the structure, in which they are aided by the Puppeteer Nessus [unrelated to the web manager, although she tries to bluff us sometimes], they are shot at by the Ringworld meteor defence, crashland on the immensely strong Ringworld floor, are captured by automatic police machinery and attacked by natives.
Finally they escape with the help of a thousand-year old ship's prostitute and a piece of very thin wire.
Sounds improbable? Perhaps, but it's a very good read and swept the boards in Science Fiction Awards in the early seventies when it was first published.
Niven's best-known novel brings together Nessus & Louis Wu from previous Known Space stories
Ringworld has spawned 3 sequels and a role-playing game, among other things. Though it was first printed in 1970, it appears farther down the list in Niven's published bibliographies.
Reprints Characters Awards Notes Spanish, as Mundo Anillo from Ediciones Martínez Roca, S.A.; as Burattinai Nel Cosmo, from Andromeda (Dell'Oglio); paper, 1972 and 1976, as Ringwelt, from Bastei Lubbe (West Germany); hardback, as L'Anneau-Monde, from Editions Opta, Paris, 1973 (nice interior covers); paper, as Ringwereld, 1972, Elsevier Nederland B.V., Amsterdam/Brussels, reprinted 1980; cloth, 1978, Hayakawa Publishing, inc.; British Editions: Science Fiction Book Club, Newton Abbot, February, 1973 (Bound in purple paper boards with gold lettering on the spine).; Orion/Gollancz hardcover, Volume VIII in the "SF Masterworks" hardcover series; Easton Press, leather-bound edition; Serbian and Croatian language editions; Audio book: Blackstone Audio Books, read by Patrick Cullen, January 1996; Audio book: Books On Tape, read by Connor O’Brien, 1997.