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
Chicago Water Tower Pumping Station, it drew clean water from water cribs in Lake Michigan. The tower gained prominence after the Great Chicago Fire of 1871. While some incorrectly believe that the tower was the only building to survive the fire, a few other buildings in the burned district survived along with the tower. The tower was the only public building in the burned zone to survive, and is one of just a few of the surviving structures still standing. In the years since the fire, the tower has become a symbol of old Chicago and of the city's recovery from the fire.