Aon Center (Chicago) Aon Center (Chicago) The Aon Center (200 East Randolph Street, formerly Amoco Building) is a modern supertall 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
Elgin Tower Building 1999 to showcase its architectural merit. Stickling died later that year, but his benefactors transferred the building to the William R. Stickling Charitable Foundation, who currently maintain the building. An addition was built in 1999 to house, rent-free, the Downtown Neighborhood Association, who intend to revitalize the downtown area. The tower was added to the National Register of Historic Places on May 22, 2002. The Elgin Tower Building is located at 100 E. Chicago St. in Elgin, between Douglas and N. Grove Avenues. This area has historically been known as Fountain Square, generally accepted as the downtown area of Elgin.