In one of the anthologies for Larry Niven (either N-Space or Playground of the Mind), he describes a Ringworld that induces magnetic effects on its star to shoot out a jet of plasma, using that to propel the whole system.
While trying to find an online reference for this, apparently in the last Ringworld novel they hook a hyperdrive up to this, making it the largest "ship" I know. (I use "I know" advisedly... I'm sure somebody somewhere has turned a multiverse into some sort of ship for some reason or other.)
In the Cities in Flight series by James Blish, the planet "He" gets about quite well, though that is dwarfed in every measurement by the Ringworld.
While trying to find an online reference for this, apparently in the last Ringworld novel they hook a hyperdrive up to this, making it the largest "ship" I know. (I use "I know" advisedly... I'm sure somebody somewhere has turned a multiverse into some sort of ship for some reason or other.)
In the Cities in Flight series by James Blish, the planet "He" gets about quite well, though that is dwarfed in every measurement by the Ringworld.