Environmental detected this almost invisible cabin in the woods while marking the trees. The spot chosen for the cabin was well thought and it was so well camouflaged that the worker was able to notice it only from 12 feet. He said it wasn't visible from 100 feet. But what was really fascinating about it is that it wasn't some ramshackle but a very solidly built cabin with concrete block foundation and stout frame. It was very organized inside. No one was home.