Ringworld

Winner of the Hugo and Nebula Awards for best novel
Four travelers come to the ringworld. . . 
Louis Wu: human and old; bored with having lived too fully for far too many years. Seeking a challenge, and all too capable of handling it.
Nessus: a trembling coward, a puppeteer with a built-in survival pattern of nonviolence. Except that this particular puppeteer is insane.
Teela Brown: human; a wide-eyed youngster with no allegiances, no experience, no abilities. And all the luck in the world.
Speaker-To-Animals: kzin; large, orange-furred, and carnivorous. And one of the most savage life-forms known in the galaxy.
Why did these disparate individuals come together? How could they possibly function together? 
And where, in the name of anything sane, were they headed?