The Willis Tower, formerly and still commonly known as the Sears Tower, is a 110 story, 1,451 foot skyscraper in the Loop of Chicago, Illinois. Designed by architect Bruce Graham and engineer Fazlur Rahman Khan of Skidmore, Owings and Merrill, it opened in 1973 as the world's tallest building, a title it held for nearly 25 years, and it remains the third tallest building in the Western Hemisphere and the 26th tallest in the world; more than 1.7 million people a year visit its Skydeck, the highest observation deck in the United States.
Facts
Year Created LocationThe Loop, Chicago, Illinois, United States 1 Architectural StyleStructural Expressionist skyscraper design (bundled tube system) 1 Structural SystemBundled tube structural system: nine framed steel tubes in a 3 by 3 matrix, some set back at upper floors 1 Primary MaterialAnodized aluminum and black glass facade over a steel frame 1 Building TypeSkyscraper (office tower) 1 Height (metres) Storey CountCounted as 108 stories by standard methods; the building's owners separately count the main roof and mechanical penthouse roof as stories 109 and 110 (Wikipedia, structure paragraph). Current UseOffice tower with a public observation deck (Skydeck); largest tenant United Airlines 1 Visitor AccessPublic observation deck (Skydeck) open to visitors; office floors are private tenant space 1 Connections
In Form
Bundled-tube skyscraper in Chicago, formerly the Sears Tower.
In the Other Atlases
Sources
1. Willis Tower (Wikipedia)
WikipediaLead section, first sentence
The Willis Tower, formerly known and still commonly referred to as the Sears Tower, is a 110-story, 1,451-foot (442.3 m) skyscraper in the Loop of Chicago, Illinois, United States.
Structure paragraph, second paragraph
The tower has 108 stories as counted by standard methods, though the building's owners count the main roof as 109 and the mechanical penthouse roof as 110.
Structure paragraph, third sentence
The facade is made of anodized aluminum and black glass.
Lead section, second sentence
it opened in 1973 as the world's tallest building, a title that it held for nearly 25 years.
Lead section, fourth sentence
Each year, more than 1.7 million people visit the Skydeck, the highest observation deck in the United States, making it one of Chicago's most popular tourist destinations.
Structure paragraph, second paragraph, tube design sentence
Graham and Khan designed the building as nine square "tubes", clustered in a 3x3 matrix; seven of the tubes set back at upper floors.
Genre reference
The Willis Tower, formerly and still commonly known as the Sears Tower, is a 110 story, 1,451 foot skyscraper in the Loop of Chicago, Illinois.
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