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
Chase Tower (Chicago) and Monroe streets. Before the building was constructed, the Morrison Hotel, on its former site, was demolished in 1965. The building first opened in 1969 as First National Plaza. When constructed, it was the headquarters of First Chicago Corporation. In 1998, it became the headquarters for Bank One Corporation, and accordingly it was renamed Bank One Tower, The current name dates from October 24, 2005, after Bank One merged with Chase. Chase's retail bank division is based in the tower. Since May 2005 the National Public Radio show "Wait Wait... Don't Tell Me!" is taped on Thursday nights before a