I started building tree houses out in our yard at a very early age. I actually started by just climbing up branches and sitting up in the tree, but eventually added some two by four platforms and just kept building from that starting point. My grandfather built my brothers and I a very nice tree house, and it had a trap door that you had to access by climbing a ladders. I have included some tree houses that are much nicer, but still remind me of the good old days when I spend time building this fortresses in the backyard.
Treehouse in Colorado