I read a great sci-fi book years ago but cannot locate it now! It was about a guy trying to get salvage from an abandoned world which had been built in rings around a star. Each ring being closer to the star (the needed energy source). This guy and his "crew" progress from one ring to the next traveling toward the center of the world. On the way one guy gets sliced in half by a high pressure hydraulic fluid when he tries to salvage a device by cutting the attaching hose. They run into a stasis zoo where one of the exhibits is another human with his head about to be bitten off by an alien. Finally at the center of the world they find a conveyor leading "out". One of the people ride the conveyor and ends up in a place for "advanced beings". There he discovers that the world was created by a bovine race. He is taught the bovine language and being judged unready for the advanced status required there is sent back over the conveyor where he rejoins his crew.