Indoor tree house...reading nook or play area was inspired from a shop in Norway. We think this is a great idea for the home as well. A small structure like this could work well at the end of a hallway and it doubles the floor space automatically. The upstairs treehouse is a perfect secret indoor hideaway. Install a few rows of bookshelves and you've got an instant reading nook downstairs. And the best news is that because it's indoors, it's year round.