The Haunted House is an old, abandoned mansion seen in Lilo & Stitch: The Series, although some people believe it is actually haunted.
In "Spooky", it is also Experiment 300's (Spooky's) one true place after he was rehabilitated by Lilo and Stitch. When Spooky is not scaring trick-or-treaters on Halloween, he haunts the old, abandoned mansion.
This mansion appears again in "The Asteroid" when Stitch convinces Spooky to come with him and Lilo to save Earth from an approaching asteroid. Spooky even transforms himself into an asteroid to clarify what Stitch was talking about, then expresses dismay.
This mansion appears briefly in "Checkers" when Stitch and Reuben summon Spooky to join them in a rebellion against Gantu. Spooky even transforms himself into Gantu to clarify what Stitch and Reuben were talking about, then gives them the thumbs up sign to show he's in.