Planet Spaceship: Some of the largest city-ships (and, of course and rather more frequently, drifts and drift clusters) can reach large asteroid/small moon size fairly readily.

Offset somewhat, non-moving-under-power-habitat-wise, because when you’re in space, it’s not like you actually need to connect structures together to make ’em stay usefully together. (Just apply occasional station-keeping thrust on a per-element basis.) It’s not like it’s going to fall down if it’s not a single rigid structure, belike.