Castle Grayskull

Clipped Wikipedia: The origin of Castle Grayskull was related in the read-along book "Castle Grayskull" as once being the beautiful "Hall of Wisdom," the "center of Eternian culture and a storehouse of all knowledge of the universe." The Hall was the meeting place of the Council of Elders. One day, the elders saw a vision of a beautiful woman dressed in snake armor (note that this description matches early versions of Teela AND the Sorceress, see for example, making an intended identity with the Sorceress very possible) who warned of future danger and also the coming of He-Man. The elders concentrated all of their power into a magical orb. The elders then magically transformed the Hall of Wisdom into Castle Grayskull in order to frighten away intruders and protect the orb. This was to have all taken place several centuries before the coming of He-Man. The Castle was then largely forgotten until Man-At-Arms eventually led Prince Adam to Castle Grayskull, where Prince Adam became He-Man using the Sword of Power.