This is NOT Mary Pope Osborne's Treehouse. You will see what I mean when you visit this site.
This series is so BOY that I - not being a BOY - had trouble reading the first book. Andy and Terry started with a 13-story treehouse. Then they added 13 more stories in the second book, The 26-Story Treehouse. Can you guess the title of the forthcoming book?*
This treehouse does not have magic time-traveling powers. It DOES have the scariest roller coaster in the world and a baby dinosaur petting zoo, 2 or more swimming pools, and an anti-gravity chamber. Among other things.
Check them out. Click here.
* Here's a hint: