Wright designed a tower for the S. C. Johnson research laboratories to balance the predominantly horizontal composition of the Administration Building. The project gave him the first chance to build the cantilevered high-rise ideal he had earlier conceived in the 1920's. The design of the Research Tower consists of fourteen levels, seven of which are square plans with a circular mezzanine above. The central structural and circulation core accommodates the elevator and stairway channels as well as necessary ventilation and services. From the central core, the floor slabs are cantilevered out like branches of a tree. The entire outside surface is sheathed in glass tubes like the adjacent Administration Building to admit light without a view. The single reinforced concrete foundation for the central core is called the "tap root" and was based on an idea originally proposed in 1929.