Designed by Frank Lloyd Wright more than 56 years ago, the innovative research tower and administration building for the S.C. Johnson & Son Inc. complex in Racine, Wisc., represent the versatility and endurance of concrete. The material was used extensively throughout both structures. In the workroom of the administration building, large, round concrete petals at the top of slender columns create a continuous, multisupport, rigid concrete frame. Wright's unique column design, which he called "dendriform," or tree-shaped, used high-strength concrete (for that time) and expanded mesh and steel reinforcement. The tallest columns, 21 feet in the workroom and 31 feet in the lobby, are mostly hollow, with walls only 3 inches thick. In addition to using cast-in-place concrete for the columns, Wright also used the material in the building's floors, roof, and walls. The research tower, also designed by Wright, features a central, hollow, reinforced-concrete core from which alternating square and round concrete floors are cantilevered. The tower's unique foundation, dubbed a "taproot" by Wright, is 54 feet below-ground. Each of the tower's seven levels consists of a pair of hollow, tapered slabs--one round and one square--with upturned edges. The core of the tower required the use of specially curved wood forms built to precise specifications. The cantilevered floors contain large amounts of welded steel mesh and rebar.