Arguably Niven’s best solo novels, as well as the ultimate BDO (Big Dumb Object) story. Great adventure in an incredible setting with trademark Niven “quirky characters”. They’re not perfect but the sense of wonder created is second to none.
Interestingly, the premise of The Ringworld Engineers, that the Ringworld is unstable, was figured out by physicists after the first novel was published. At the 1971 World Science Fiction Convention, MIT students were chanting “The Ringword is unstable!” Hence why our heroes need to fix the problem.