This 3D model was originally created with Sketchup 8 and then converted to all other 3D formats. Native format is .skp 3dsmax scene is 3ds Max 2016 version, rendered with Vray 3.00 Eric suggested that I put a cellar under my Fortress. Well, I am a nice guy, so here it is. Only accessible by walking down there, it is rather nondescript, with room for all your excess stuff, plus the water heater and furnace. Measures only 20'X40' with a 9' ceiling and a steel beam.. Also added a dirt plot around the Fortress. As far as the 2' thick walls, they are poured concrete with brick, stone veneer and furring with an insulated inner core. See castlemajic.com for details about walls.