Hmmmmmmmmmm............well, have several thoughts all of which I'm sure are wrong!!! Thought of a "Mushroom" house or a "ManyRoom" house and then I remembered the moon and the tree you mentioned and I thought of a
"MoonRoom" house and the last thing that entered my brain, again considering the moon and the tree, was the school in the Harry Potter series with the Whomping tree and the moon but I can't remember the name of the school. Then I thought of a more traditional building like a museum but not enough letters.......hmmmmmmmmmmmmm