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
Joshua Sears Building "SEARS". The second entrance is centered on the east facade and bears many of the same features: pressed metal pediments, etc. The Sears Building was built in 1891 by Boston millionaire, philanthropist and Kirkland investor Joshua Montgomery Sears as part of the speculative land boom following Peter Kirk's proposal of building a steel producing mecca that would rival Pittsburgh on the east side of Lake Washington. The building cost $18,000 to build, at the time the most expensive being built in Kirkland outside of the steel mill itself. The bricks were pressed from local clay at Peter Kirk's own brick