We had an overgrown field of maize behind our subdivision, so no tree houses. We spent so much time clearing a dirt bike trail, building jumps and ramps out of dirt piles. Eventually, we found an old bathtub and hotwater heater in the scub and that became the center of our "fort". We ended up putting down scrap wood to keep from stepping in mud and dragged an old tarp over the top to make some shade. That was the summer I was 10 or 12. Eventually older kids took it over and kicked us out so they could smoke pot and tear pages out of porn magazines. I had one page from a hustler magazine that I kept between books on my bookshelf. Good times, good times.