One Two Pru was one of the first skyscrapers built in Chicago after World War II. It had the highest roof in the city at the time, slightly taller than the Chicago Board of Trade Building. This 41-story Art-Deco-influenced Modernist behemoth was built above Illinois Central Railroad air rights. It was one of the first and largest Chicago buildings to be built over existing rail lines. It essentially sits atop stilts that meet the ground at 500 separate spots. Each small piece of land was acquired individually from the railroad in anticipation of the building. A bas relief of the Rock of Gibraltar (Prudential’s logo) by sculptor Alfonso Iannelli is prominently visible on the exterior of a 1968 addition. A 73-foot broadcast antenna for WGN was also added. Since the 1990 completion of neighboring Two Pru, the building has been referred to as One Pru.