The Treehouse is the home of Lock, Shock, and Barrel, Oogie Boogie's three henchmen. Its location is just outside Halloween Town on the farside of the Graveyard Hill. The tree is in the middle of a pit that makes up part of Oogie's Lair. A small rope bridge leads to a cage shaped elevator that carries the three up into the house.
The house itself is the setting of the song Kidnap The Sandy Claws, and is loaded with bugs and torture devices. This includes bear traps, spiked clubs, axes, poison, a bathtub with legs, a catapult, and many other "toys".
Early Concept Art of Lock Shock and Barrel's Treehouse
Setting with Lock Shock and Barrel in there Treehouse with the bathtub at Disney-MGM Studios in 1994 at the Backlot Tour