Abstract: An open skeleton-frame building system comprising a plurality of interconnected block elements. Each block element includes six sides, eight corners, and a rectangular base. Four column base plates are placed within four interior angles of the rectangular base. Four upstanding columns are placed on top of each of the four column base plates and serve as lateral supports for side walls. A lower load-bearing beam rings the perimeter of the rectangular base, interconnecting bottoms of the four upstanding columns, and serves as a bottom support for side walls. A lower outwardly projecting beam is attached to the outside edge of the lower load-bearing beam and serves as a bottom retainer for either an outer building wall or an interior fire wall with a block element interconnected at a lateral side.