Mr. Philipson likes to call it the ‘Silent Giant’, as the Aon building has been around since 1973, but never attracted the fame that some of its rival Chicago skyscrapers had received; namely, the Willis Tower (formerly the Sears Tower) and the John Hancock Tower. All three built between 1973 and 1974. The Aon has not been mentioned much in the trade magazines or articles, compared to the amount of articles discussing the other skyscrapers.
It is currently the third tallest building in Chicago, after the Willis Tower and the new Trump Condominium; however, in the early 1970s, before the Asia skyscraper market took off, it was the tallest in Chicago and the fourth tallest in the world.
The Aon building stands 1,136 feet high and still ranks among the 25 office buildings in the world to reach over 1,000 feet. With its marble facade, It became the world’s tallest marble-clad building, containing 43,000 slabs of Italian Carrara marble, but it was determined that the marble panels were too thin to withstand extreme temperatures, so the entire building’s facade was reclad in the early 1990s, using Mount Airy white granite at cost of over $80 million.
The building design reflects the ‘straight up and down’ style that was prominent in the 1960s and 1970s. It provides no setbacks, no spires, no atriums nor any other aesthetic design, but it does carry some appeal with its powerful looking granite curtain wall facade that stretches 83 floors.
With that said, the Aon building does add significantly to the Chicago skyline.