This is book one of a series of five books.
The year is 2850. Louis Wu is 200 years old, bored and looking for adventure. So when an alien creature known as a Pierson’s puppeteer invites him on a private expedition with two others, he says yes. Where he ends up is the most stunning construction ever seen by man. Ringworld.
Ringworld is an artificial ring that encircles a sun. A structure so large it defies imagination. 186 million miles in diameter and 1 million miles wide. Spinning at 770 miles per second to create gravity on the inner surface. Huge walls at each edge hold in an atmosphere. Rotating within the ring is another smaller ring of equally spaced shade squares which periodically block the sun creating a day night effect. Who built Ringworld, and why, is a mystery.
As they attempt to land their ship it is shot down by an automated defense system intended to destroy asteroids. Stranded, they must search Ringworld for some way to repair their crippled ship, while at the same time unravel the mysteries of this amazing artifact and those who live on it.