Built by a powerful group of superheroes, the Graveyard of Giant Robots is a massive cavern in the upper mantle of the Earth. The old heroes stored dead kaiju, wrecked alien spaceships, and decommissioned giant robots in the Graveyard. Eventually the superheroes used it to throw anything that wasn’t too hazardous or useful. It is accessible by teleport pads in various superhero bases and a single maintenance tunnel network that connects somewhere on the surface. A system of repair and defense robots keep the facility sealed and intact, but they seldom pay attention to anything that does not threaten the integrity of the outer walls. An extensive climate control system creates weather inside the Graveyard. The scientists built it to speed along the decay of kaiju corpses and prevent the build-up of noxious fumes. Artificial sunlight comes in a regular cycle of day and night. It is a self-sustaining ecosystem.