Princess Snake's mansion appears in the episode "Princess Snake's Hospitality", in which Princess Snake attempts to kidnap Goku and prevent him from reaching the end of Snake Way where King Kai's Planet is. King Yemma is the only person said to have ever escaped the mansion alive, aside from Goku.
In reality, the mansion appears to be an illusion, as Goku enters the mansion through a giant snake head, and it is revealed that he is in Princess Snake's innards once he demonstrates that he does not plan to stay, angering the princess and causing her to reveal her serpentine form. It is possible that Princess Snake and her servants' motivation for keeping Goku in the mansion is to make sure he is digested.
Video Game Appearances
It is an area in the Other World in the video games Dragon Ball Z: Harukanaru Densetsu and Dragon Ball Z: Attack of the Saiyans. Enemies encountered here in Attack of the Saiyans are Mansion Snake, Patrol Ghost, Princess Servant, Princess' Guard, and the boss is Princess Snake in her Princess and Snake forms.