Cageworld 1

"World upon world had been added, each planetary orbit studded with new planets. Planet had been linked to planet until unimaginably vast concentric shells, spinning, stabilized, surrounded the sun. Each shell teemed with the countless billions of humanity. And always unceasingly the work went on..."Out on Mars shell the question had arisen - was there really a central sun or was it just a myth out of the remotest time. To hunt for the sun meant to go through the intervining shells - an expedition that had never been attempted. But there were three who were ready to go: a master assassin, a master illisionist, and a mistress of the erotic arts.To find the sun, to outwit Zeus the planet-sized computer that directed the continual expansion of the Solalr shells, this would be the greatest adventure of half a million years - and the first of several!