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
The Gogo Building district along the Chicago River. There are two large red brick buildings along the Chicago River just south of where the river splits, formerly known as the Butler Brothers Warehouse buildings. They were both designed for the Butler Brothers Company, a mail order company, similar to Montgomery Ward's and Sears & Roebuck at the time. The northern structure was designed by Daniel Burnham, a famous Chicago architect, with its completion date being 1913, a year after Burnham’s death. This building only stood for 7 years before being completely demolished and rebuilt exactly as it stood before by the Chicago Union