Luna
Luna is Earth's only moon. It is also where the Ur-Quan Kzer-Za stationed ships from their Battle Thrall fleets to watch after the Hierarchy's interests after the First War.
Originally several Ilwrath and Spathi ships were left here to watch the Humans. The Ilwrath left almost immediately, presumably because watching over prisoners with no chance of escape had displeased their cruel gods Dogar and Kazon. The Spathi remained for some time but grew fearful of the remote possibility of a human surprise attack. They also grew worried of their homeworld's defenses should the Ultimate Evil attack. Ships and crew returned one by one to Spathiwa while the base was moved farther and farther out toward the edge of the Solar System, eventually leaving one Eluder and it's Captain, Fwiffo, on the surface of Pluto.
Luna itself was left with automated dirt movers and fake radio broadcasts meant to fool the Humans into believing that they were still well guarded.