One of the classic Big Dumb Object novels of the 1970s, which won the BSFA Award for 1975 (other nominees not recorded; also got third place in the 1976 John W Campbell Award, Silverberg's The Stochastic Man coming second and no award made for the top spot; this was the year that The Forever War won Hugo and Nebula). It's rather of its time, which is to say that the evil ruler is all the more evil because she is a woman, and the hero's wife doesn't get to do much more than be his wife (he bravely fends off sexual advances from one of his own crew in a moment of crisis). In fairness, Shaw was good at portraying troubled marriages (always from the male partner's point of view) in his fiction, and this is another case in point. Orbitsville itself is a Dyson sphere, totally enclosing a star at earth-orbit distance, which our hero stumbles upon after fleeing the evil ruler; I felt a bit short-changed in that Shaw concentrates on the human politics of his story and devotes much less time to describing it than Niven does Ringworld or Clarke does Rama, and we end up in the climactic section of the book just doing a long aircraft trip across relatively featureless landscape. Perhaps the sequel has more stuff that I would like in it.