Architecture of Chicago a new structural system of framed tubes in skyscraper design and construction. The first building to apply the tube-frame construction was the DeWitt-Chestnut Apartment Building which Khan designed and was completed in Chicago by 1966. This laid the foundations for the tube structures of many other later skyscrapers, including his own constructions of the John Hancock Center and Willis Tower (then named the Sears Tower) in Chicago and can be seen in the construction of the World Trade Center, Petronas Towers, Jin Mao Building, and most other supertall skyscrapers since the 1960s. Willis Tower would be the world's tallest building
Equitable Building (Chicago) Equitable Building (Chicago) 401 North Michigan is a 35-story skyscraper in the Streeterville area of Chicago, built in 1965 at 401 North Michigan Avenue, along the north bank of the Chicago River. Along with the Tribune Tower and Wrigley Building, it forms the southern gateway to Chicago's famous Magnificent Mile. The building was built atop the site of a cabin belonging to Chicago's first permanent resident, Jean Baptiste Pointe du Sable. In reference to du Sable, the large plaza adjacent to the building has been named Pioneer Court. 401 North Michigan occupies a site with several aspects of historical significance,