When I was a kid, I had several tree forts. I say forts and not houses because these were designed to keep certain people out (namely my little sister). The culmination was a sound structure 10 feet up in a tree, complete with a small bench, a pseudo basement for storage and a pole to slide down for quick escape should my little sister and her doles overrun us.
After we moved when I was in 4th grade, my want of tree forts waned. Soon after, however, I discovered the manic awesomeness that is the Cold War. The sheer power of weapons never fired, bombs never dropped and clandestine operations actually carried out captured my interest. I always wanted a bomb shelter, and after reading this link, I want even more. Not to launch my post-apocalyptic rise to power, but because knowing my bomb shelter is under the ground unknowing people walk on is kind of cool.
It might be my nerd’s version of a “tree house,” but this time, I would let my little sister in.