I've just finished re-reading the Ringworld trilogy, after maybe 15 years or more.  A well told science fiction tale that keeps you interested all the way through.  Very thought provoking....

90% of the story occurs on the Ringworld, which is a ring around an alien sun with approximately the same diameter as earth's orbit. 

The first book was written in 1970 by Larry Niven; pretty good stuff for that far back.

i liked it too