Hexagon/Roundhouse Combination (click to enlarge)
Specifications: 18′ interior diameter roundhouse = 254 sq. ft., roundhouse loft = 248 sq. ft., 20.5′ hexagon = 372 sq. ft., total = 874 sq. ft. interior, Footprint: 28′ x 44′
Description: In this unique design, a two story roundhouse adjoins a hexagon. Features include a large bedroom in the round, a wood stove insert built into a central stone column, and a large loft above the bedroom for use as a home office, etc.
Hexagon/Roundhouse Combination (click to enlarge)
Earthbag House Plans 
The stone column could also be built out of CEBs, adobe or recycled brick.
The building could be turned so the center of each structure is on an east-west axis.