he lustrous ceiling is supported on concrete columns whose tops swell into broad caps resembling lily pads, prompting Wright to compare the space to a forest glade. Structural engineers were skeptical of the design’s integrity, however, and in a now-legendary episode Wright loaded a test column with sand bags to demonstrate its ability to support the roof.

The natural metaphor is expanded in the Research Laboratory Tower. Here, concrete floors recalling tree branches are cantilevered from a central shaft or trunk which encloses the elevator and stairs, as well as mechanical services. Outside, the Tower’s verticality acts as a dynamic foil to the Administration Building’s horizontal expansiveness.