Completely underground so it is invisible. I'd like to have a door in one of the walls. I plan on covering the ceiling with at least several inches of dirt, then lay grass. What i'm thinking is the best way would be build it into a hill, at like a 45 degree angle, so maybe only one partial wall with door is exposed. I can always camoflauge it somehow. I have over ten acres so i'm not that worried about someone seeing me construct this room. What do ya know, i might be in Tenn but as far as i know i don't live on top of a f ing huge cave like that.