Gruntilda's Lair is located in a large sculpture of Gruntilda's head in Spiral Mountain. It is largely cavernous but features some wild changes in environment (including a swamp, a snow-filled area, a forest and an enormous lava-filled chamber). Most of it is indoors, but the graveyard area where the Mad Monster Mansion entrance is to be found gives the impression of being outside. It is also the location of all the jigsaws that must be filled to open the worlds. The background music of Gruntilda's Lair is based on the tune of Teddy Bears' Picnic and is also used as the theme for Gruntilda herself.