Castle Grayskull sits at the center of the known universe on the planet Eternia. It houses the very power that created the cosmos, it serves as home to the Sorceress and refuge to He-man and the Heroic warriors of Eternia. It is the center of many battles thru out the cartoon series and various comics/magazines as Skeletor and his evil warriors make attacks to claim the castle and the great power that rests within its walls.