The Earthcom 70 is a 180 deg elliptical arch with an inside dimension of 70 feet long, 12 ft wide, and 23ft 9inches high at the center. It can be used an an atrium or as an actual shelter. Most EC70's are composed of 6-20 archs (72-240 ft long) and all can be joined by various tunnels and entranceways. this structure is usually designed as a two level structure with living condos at ground level and storage supplies on the second level.