17.5" x 17.5" (444mm x 444mm) footprint. Stackable structure can built as a single unit (floors glued together) or as individual modules so you can stack and unstack as you wish. The minimum pieces you'll need are a ground floor and a top floor, but you can also add as many middle floors as you like to make a structure as tall as you want.
Generic design should fit well in most regions of the world and most time periods from WWII forward and into the future!
