The Aon Center (200 East Randolph Street, formerly Amoco Building) is a modern skyscraper in the Chicago Loop, Chicago, Illinois, United States, designed by architect firms Edward Durell Stone and The Perkins and Will partnership, and completed in 1974 as the Standard Oil Building. With 83 floors and a height of 1,136 feet (346 m), it is the third tallest building in Chicago, surpassed in height by the Willis Tower and the Trump International Hotel and Tower. The building is managed by Jones Lang LaSalle, which is also headquartered in the building. Aon Center formerly had the headquarters of Aon and Amoco; Aon's US operations are still headquartered here.