Frank Lloyd Wright’s Unity Temple was entirely constructed from reinforced concrete, which was cast in wooden molds. None of the structural steel is visible. Originally Wright wanted concrete with a crushed limestone aggregate for the upper walls, piers, bearing walls and column footings. The beams and floors were to be a lighter concrete mixed with cinder. Once realized that the wall surfaces and cores could be poured as a whole, the limestone aggregate was replaced by cinder and reinforced with steel rods. The concrete was poured in layers of six inches to ensure solidity and that the aggregate would not separate out. Wright used a mortar finish that was applied to the interior of the molds. Granite was the first choice, but gravel was used instead due to cost issues. Oak is used on the interior and casein paint was applied to the plaster walls. Art glass was used in the skylights. Upon opening, Unity Temple was praised by the congregation for not only its acoustic properties but also its Modernist design which expressed their liberal faith and successfully joined the school, place of worship, and meeting rooms. Beyond the congregation, the design and the use of concrete was praised by the public. The move towards an ultra-functional building using new construction techniques was viewed as the epitome of modern architecture.