Unity Church was the first public building of any type in America to be built entirely of exposed concrete. Its use was dictated in part by the need to keep construction costs low, but Wright's principle of integrity called for the building to be "thoroughbred, meaning built in character out of the same material," and therefore reinforced concrete was the only material possible. Most critics consider this sanctuary one of Wright's highest achievements. The ceiling is opened above the central cube into a grid of beams, into which are set 25 stained-glass skylights. Clerestories run full width across the tops of each balcony just under the roof. Light enters the sanctuary only from above and is filtered by the colors and patterns of the leaded windows and skylights. As Wright said, the space is flooded "with light from above to get a sense of a happy cloudless day into the room... the light would, rain or shine, have the warmth of sunlight." Composite floor plan of three levels. The architect's imaginative use of the limited space on the building site provided ample accommodations for the 400-member congregation in both the sanctuary (Unity Temple) and the parish hall (Unity House). The plan is closely related to the centralized churches of the Renaissance, being similarly based on pure geometries of the square and cube. Drawing copyright © the Frank Lloyd Wright Foundation. For more information about Unity Church www.unitytemple.org References: Frank Lloyd Wright by Robert McCarter, ©1997 Phaidon Press Limited; The Architecture of Frank Lloyd Wright by William Allin Storrer, © 1995 MIT Press