Bart often comes to the treehouse with friends, mainly Milhouse.
It once housed a casino.
It was destroyed two times: The first time was when Mr. Burns stole Springfield Elementary School's oil, and the stream of oil hit the treehouse. Bart and Santa's Little Helper were inside at the time; Bart quickly recovered from his injuries, but Santa's Little Helper's hind legs were broken, and he required both a cast and a crude wheel brace. At the town meeting that preceded Mr. Burns' shooting, Bart referred to Santa's Little Helper's injuries as his reason for being mad at Burns (although he needed to clarify after his reference to "[Bart's] best friend" had the populace thinking that Burns did something horrible to Milhouse).
When Bart and his friends were trying to listen in on Lisa's tea party with her friends, Lisa saw the paper cup which the boys were listening from and pulled it. Then the boys started pulling it, and it turned into a tug of war, until Bart's treehouse fell apart due to the pressure of Lisa's pulling on the tree. Then, after Homer's disastrous attempt and getting a plan for the treehouse (which turned out to be for a go-kart track) and stealing railroad ties for wood, Marge called on the Amish. The Amish put together the treehouse pretty quickly, but the grand opening turned into a disaster when Homer switched the electricity on (put together by the Amish) and the electric wire exploded and the whole treehouse was set alight. Homer got trapped in the treehouse, but when Santa's Little Helper went to "save" him, he dragged out the turkey instead. Snowball II ran up, and Homer, unconscious on the floorboards, was woken up (or rather scratched on the chest) by the cat, and was led out of the window safely.
Bart once held a Playdude party in his treehouse, inviting many friends over to it. Mario also used Bart's treehouse to avoid the trash cans been thrown by Homer after he annoyed him but he is struck by one.
It was destroyed a third time by the populace when they shot at a sinkhole that the family had just escaped through, before being rebuilt, along with the Simpsons' house, in the aftermath of Trappuccino. Once, when Bart escaped from Jimbo after he discovered that Shauna, his girlfriend, was cheating on him with Bart, he hid from the bullies in the treehouse with Shauna.
In "Simprovised", Marge rebuids the treehouse in a much better version.
It is a small house made of wood with a ladder leading up to it and a secret entrance in the floor. It's got a couple of windows as well as the door. The interior of the treehouse often changes, usually it contains only rudimentary furniture, but other times extravagant furnishings.
- In different episodes the treehouse has been seen in different locations of the backyard.
- After building the treehouse in The Simpsons: Tapped Out you unlock (and watch) the third cut-scene in which Homer collects the money and XP dropped by the treehouse while going round Bart who fell out the tree after it was built.