We Build a Fort.

The tree fort had more to do with my education than anything else in my childhood
The best part about our new property was a couple really great fort building trees. There was an old Siberian Elm that had been bent to the ground on one side when it was young so the main trunk and that branch formed two ready made walls. We added two others and a roof out of pieces of scrap lumber and we were on our way. 
16 Penny nailed it!
My mom and dad were hands-off parents and we spent hours and hours building our forts to new heights. Instead of spending our allowance on candy every week we started buying nails. 16 penny was the most common. If we found ourselves flush with cash, say five dollars in birthday money, we would splurge and buy some glue coated nails we called “sinkers”. I am not sure that was their proper name. 

After the main floor was done, we started building a platform on some branches about ten feet off the ground. The deck was eight foot square with two-by-four supports. It was drastically under-built by even the most lax of third world standards. Whenever a side would slump we would add in more supports to prop it up until a tenuous treaty with physics was reached. The walls were made of discarded wall paneling and as such were not safe to lean against, a mistake that sent many kids to the ground. 

We built a higher platform for observation and a high-rise tower that had four levels made of old doors that were offset front to back to allow an access hole to the next level if you crawled across the length of the door. The project took several years to get this large and in that time my father had never come back to see what we had created. When he did, he was concerned about how unsafe it was. Many of the levels were sparsely built and twelve feet off the ground. He made us tear it most of the way down, leaving only the ground floors and our one elevated platform. 

I hated him for making us do that.