All children have or would like very much to have a tree house. They can spend a whole day staying there, hanging from the tree, with the head in the leaves, imagining they are little Tarzans or some other movie characters. But when you grow up you become more serious and forget all about this fun habit. I wonder why? Apparently some adventurous guys from Portland, Oregon, USA, had the courage to build their own tree house, a whole lot bigger than usual in the middle of a forest. They used only natural building materials like wood and stones, of course combined with some glass for the windows.