The Armstrong Rubber Co. / Pirelli Tire building is a fantastic embodiment of the design ideals held by a master Modernist architect, Marcel Breuer. The entire building is a composite of steel structure for the 4-story tower and long-span concrete T-beams for the two-story high-ceiling test area. Between these two parts of the building is a 2-story gap, giving the tower portion the illusion of suspension. Enveloping the entire building are pre-cast concrete panels of varying scale and design, depending on the function they enclose. Breuer preferred concrete as a building material, as he viewed it as universal – it serves both architectural and structural functions of the building. The pre-cast concrete panels are modeled in a form which Breuer termed crystalline. This form provided protection from the sun (a Breuer preoccupation) and gave the façade a tremendous physicality and depth. The end result is a continually changing impression of the building, depending on the day, the season and the weather.