The Aon Center is a modern supertall skyscraper located in the Northeast corner of the Chicago Loop, Chicago, Illinois, United States, designed by architect firms Edward Durell Stone and The Perkins and Will partnership, and completed in 1973 as the Standard Oil Building. With 83 floors and a height of 1,136 feet, it is the fourth-tallest building in Chicago, surpassed in height by Willis Tower, Trump International Hotel and Tower, and St Regis Chicago.