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
Randolph Tower Randolph Tower Randolph Tower, formerly known as the Steuben Club Building, is a historic Gothic Revival skyscraper in Downtown Chicago. The building was constructed in 1929 and designed by architect Karl M. Vitzthum, who designed another Chicago landmark, the historic One North LaSalle Building. Randolph Tower was built for the Steuben Club of Chicago to promote German-American heritage. After the first World War, American citizens of German descent sought to found clubs to serve as a testimonial of their loyalty to the ideals of American citizenship. The first 25 floors were built for retail and offices and the club was