Willis Tower


Willis Tower,

formerly the

Sears Tower,

Chicago, the second tallest building in the United States. Until the completion of the 1,483-ft (452-m) Petronas TowersPetronas Towers,
twin skyscrapers in Kuala Lumpur, Malaysia, that are the world's tallest twin towers. Standing 1,483 ft (452 m) high, they were designed by the Argentinian-American architect César Pelli.
..... Click the link for more information.  (1998) in Kuala Lumpur, Malaysia, it was the world's tallest building. Constructed from 1970 to 1974 for Sears, Roebuck & Co., it rises to a height of 1,451 ft (442 m) and has 108 floors as well as a 278-ft (85-m) television antenna. Designed by the firm of Skidmore, Owings and Merrill, the building is supported structurally by square tubes of welded steel with floors suspended within the tubes, a technological innovation that was developed specifically for the mammoth skyscraperskyscraper,
modern building of great height, constructed on a steel skeleton. The form originated in the United States. Development of the Form

Many mechanical and structural developments in the last quarter of the 19th cent. contributed to its evolution.
..... Click the link for more information.  by architectural engineer Fazlur Kahn. The tower has an exterior of black aluminum and bronze-toned glass cut by black bands. It was renamed in 2009.