The Castle
From GURPSworld Wiki
The Castle is the royal domain of King Haile Selassie II, and houses the Zion Colony where he resides. Unlike previous royal domains, The Castle is an entire galactic cluster, formerly known as the Norma Cluster, that lies in the area once called The Great Attractor. The precise whereabouts of the Zion Colony and the King's residence is not public knowledge, and the entire cluster of galaxies is off-limits to unapproved travel. Several large military installations, which house the bulk of the Royal Fleet, are also located somewhere in The Castle, as is the largest black hole in the Laniakea Supercluster.
The Castle comprises many giant and supergiant galaxies, and has a total mass similar to that of the populous Virgo Cluster. Despite that, The Castle is relatively underpopulated, with no more than a billion residents purported to reside there. Some galaxies in The Castle are thought to be totally uninhabited. The Castle has its own jump and communication networks that are not open to public use, but which allow for rapid movement and communication within its confines for residents and approved visitors.