The Lich's lair

The Lich King's Castle is the home of the evil Lich King. The castle has no appearances in the show so far, but was mentioned in the Lich King's pitch document. It stated that the Lich King was trapped inside the Castle, which was probably the doing of the hero Billy. In the episode "His Hero", it showed Billy infiltrated the castle and defeated the Lich King. The location and design of the castle are currently unknown, but will probably appear later in Season 2, since Pendleton Ward said that the Lich King will have a major appearance later on in the season.

Known Design
The castle was only shown briefly on the inside. The size and design of the castle are currently unknown, but it was shown that it is dark inside and that it was made of stone.

Appearances
"His Hero"

"Mortal Recoil (presumed)