Willis Tower

Willis Tower
w_lemay · CC BY-SA 2.0 · source
Name	Willis Tower
Caption	The tower as seen from the intersection of Lake and Wells Street.
Location	233 South Wacker Drive, Chicago, Illinois, United States
Coordinates	41, 52, 44, N...
Status	Complete
Start date	August 1970
Completion date	May 3, 1973
Opening	1974
Height antenna spire	1,729 ft
Height roof	1,450 ft
Top floor	1,353 ft
Floor count	108
Floor area	4,560,000 sqft
Elevator count	104
Architect	Skidmore, Owings & Merrill
Structural engineer	Fazlur Rahman Khan
Main contractor	American Bridge Company
Developer	Sears, Roebuck and Company
Owner	Blackstone (95%), EQ Office (5%)

Willis Tower is a super-tall skyscraper located in the Loop community area of Chicago. Upon its completion in 1973, it became the tallest building in the world, a title it held for nearly 25 years. Designed by the architectural firm Skidmore, Owings & Merrill and engineered by Fazlur Rahman Khan, the tower is renowned for its innovative bundled tube structural system and remains an iconic symbol of Chicago and American engineering prowess.

History

The project was initiated by the retailer Sears, Roebuck and Company, which sought to consolidate its thousands of employees from across the Chicago metropolitan area into a single headquarters. Construction began in August 1970 under the general contractor American Bridge Company, with the topping out ceremony held on May 3, 1973. For over two decades, it was known as the Sears Tower, serving as the corporate home for its namesake. In 1994, Sears, Roebuck and Company vacated the building, and in 2009, the global insurance broker Willis Group Holdings secured naming rights, prompting the controversial change to its current name. Major ownership interests have since been held by firms like Blackstone and EQ Office.

Architecture and design

The design by Skidmore, Owings & Merrill, led by architect Bruce Graham and engineer Fazlur Rahman Khan, revolutionized skyscraper construction. Its defining feature is the bundled tube structural system, comprising nine square tubes clustered together, which provides immense strength and wind resistance while reducing steel usage. The tower's stepped-back silhouette, with two tubes terminating at the 50th floor, two at the 66th, three at the 90th, and the final two rising to 108 stories, creates its distinctive profile. The exterior is clad in black aluminum and bronze-tinted glass, and the skydeck observatory was added in a 1974 renovation by the firm A. Epstein and Sons.

Observation decks

The primary public attraction is Skydeck Chicago, located on the 103rd floor, which offers panoramic views of Lake Michigan, up to four states, and the Chicago skyline. A major renovation in 2009 introduced The Ledge, a series of glass boxes that extend approximately four feet from the building's facade, providing a thrilling view straight down to Wacker Drive. Operated by Legends Hospitality, the experience includes interactive exhibits on Chicago history and the building's construction. It is one of the most visited tourist destinations in the United States.

Tenants and facilities

The tower functions as a premier Class A office complex, containing approximately 3.8 million square feet of rentable office space. Major tenants have included financial firms like United Airlines (which maintains a large operational center), Schiff Hardin, and Katten Muchin Rosenman. The building also features a large retail concourse, multiple dining options, and a dedicated Metra commuter rail station beneath the tower, providing direct service to Union Station. Its scale is such that it has its own ZIP Code, 60606.

In popular culture

The building has been featured prominently in numerous films and television series, often serving as a visual shorthand for Chicago. Notable appearances include the climax of the 1986 film *Ferris Bueller's Day Off*, where characters visit the observation deck, and its depiction in the DC Extended Universe as the daily workplace of Clark Kent. It has also been destroyed or threatened in disaster films like *Transformers: Dark of the Moon* and served as a key location in the television series ER* and Chicago Fire*.

Records and recognition

Upon completion, it surpassed the World Trade Center to claim the title of world's tallest building, holding the record until the 1998 completion of the Petronas Towers in Kuala Lumpur. It remains the tallest building in the United States by roof height and the second-tallest by pinnacle height, after One World Trade Center. The American Society of Civil Engineers has designated it a National Historic Civil Engineering Landmark, and it was listed on the National Register of Historic Places in 2018. It continues to be a defining element of the Chicago skyline.

Category:Skyscrapers in Chicago Category:Skidmore, Owings & Merrill buildings Category:National Register of Historic Places in Chicago