Abstract: A building that can be constructed quickly in a wide variety of configurations has a sill beam that runs along the perimeter of the building. The plumbing, electrical and other utility needs for the building are channeled through a cavity provided for in the sill beam. Columns are removably mounted on the sill beam according to the desired configuration with exterior and interior panels extending between the columns. Overhead, roof beams extend between columns with roof panels extending between the roof beams. Similarly, the floor is constructed of a plurality of floor panels. The panels forming the exterior walls of the building are pre-finished on both sides.