Aon Center (Chicago) the world headquarters of Aon and Amoco. Aon's US operations are still headquartered here. The building is also the co-headquarters of Kraft Heinz. The Standard Oil Building was constructed as the new headquarters of the Standard Oil Company of Indiana, which had previously been housed at South Michigan Avenue and East 9th Street. When it was completed in 1973, it was the tallest building in Chicago and the fourth-tallest in the world, earning it the nickname "Big Stan". (A year later, the Sears Tower took the title as Chicago's and world's tallest.) The building employs a tubular steel-framed structural system
Grant Thornton Tower and Exchange Commission filings. Grant Thornton Tower Grant Thornton Tower (formerly Chicago Title & Trust Center, 161 North Clark and sometimes Chicago Title Tower) is an office tower located in Chicago designed by the firm Kohn Pedersen Fox Associates. Before completion in 1990 the twin tower design was awarded The Chicago Athenaeum's "Best Building" Architecture Award, the award was received by one of the lead designers Kevin Flanagan. (view PLP Architects). The fifty-storey building rises 756 feet (230 m) in the Loop and was completed in 1992, on the site of Chicago's Greyhound Bus Station. Previously, a structure at 111