Sagittarius A*, The Galactic Nucleus is the center of the galaxy and the home of the Space Monsters. More specifically, it is the Space Monsters' central control "brain", which confused the Human Topless with other Space Monsters.
In a desperate attempt to stop the Space Monsters once and for all, It was destroyed with the Buster Machine 3 on May 22, 2048, along with a sizable part of the Milky Way's inner core.