Ringworld is a pretty much the poster child for the hard science fiction ‘big dumb object’ novel. In that way, it’s very similar to the first of the Rama series (actually published 3 years later; ). It’s light on plot and characterization, instead opting to spend much of the novel on the titular Ringworld itself.
The technology of the Ringworld itself is interesting, although a decent amount of exactly how it works and its long history are left out. Essentially, take all of the planets and other objects in several solar system and turn them into a ring roughly 1 AU in radius. Spin it fast enough that you get fake gravity by way of centrifugal motion, add overhead plates to block sunlight into a fake day/night cycle, and add some plants. Bam Ringworld.