The promise of a ship capable of traveling a light year in 1.25 minutes lures 2 humans and a tiger-ish alien known as a Kzin out into the unknown reaches of space to investigate something never before seen: a massive alien ring encircling a sun. This "ringworld" has a diamter equal to Earth's orbit around the Sun and has the surface area equivalent to 3 million times the size of our planet. Why it's there, what happened to it, and who lives on it are just a few of the questions 200-year old protagonist Louis Wu has to discover if he's ever to escape after their ship crashes on it.
Ringworld won the 1970 Hugo and Nebula awards for Best Novel, and as much as it's known for the detailed mechanics and hard science that make up the ring itself, the novel is more concerned with the questions that have served countless novels and college philosophy classes for ages: what role does Man play in the universe - the universe at large and the universe that is his immediate surroundings? What is his relationship to God? To Fate? And ultimately what determines our destiny? Each character in the novel have their own reasons for making the journey, and as motivations and hidden agendas are unearthed, the struggle to work together in order to escape become more difficult and dangerous.
And I think that might be one of the reasons I was left flat by the book. At different times it was enamored of the "hard" science fiction aspects, at other times the psychology of its characters, but at no time was the mystery of the alien world that draws them there ever fleshed out enough to make their predicament interesting. At the end I didn't really care what happened to anyone. And a surprise "I knew it all along" ending didn't help things at all.
I know Ringworld has it's fan base - there have been three sequels, games, and movies in production forever, but my response to the wonders of the alien construct is lukewarm at best, and definitely not something I'll be pursuing anytime soon.