Willis Tower

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Willis Tower

Willis Tower looking up
General information
Type Office, observation, communication
Location 233 S. Wacker Drive
Chicago, Illinois 60606
United States
Coordinates 41°52′44″N 87°38′09″W / 41.8789°N 87.6358°W / 41.8789; -87.6358Coordinates: 41°52′44″N 87°38′09″W / 41.8789°N 87.6358°W / 41.8789; -87.6358
Construction started 1970
Completed 1973
Antenna spire 527 m (1,730)[1]
Technical details
Floor count 108
Design and construction
Architect Fazlur Khan, Bruce Graham

The Willis Tower is a skyscraper in Chicago, Illinois. Sears, Roebuck and Company paid for the building to be built in August 1970. It was called the Sears Tower until 2009. The building was finished in 1973. The Willis Tower was the tallest building in the world from 1973 to 1996. It has 108 levels, and from the ground to the roof it is 442 m (1,451 ft) tall. The tower was designed by Fazlur Khan and Bruce Graham. It was the tallest building in the world for 25 years.

Willis Tower is the second-tallest building in the United States and the eighth-tallest freestanding structure in the world. The skyscraper is one of the most popular tourist destinations in Chicago. It has over one million people visit its observation deck each year. It was named the Sears Tower throughout its history until in 2009. The building's name was changed when the Willis Group received the right to rename the building. On July 16, 2009, the building was officially renamed Willis Tower.[2]

History[change | change source]

Then-Sears Tower during its construction, c. 1973

In 1969, Sears, Roebuck & Co. was the largest retailer in the world. It had about 350,000 employees.[3] Sears executives decided to combine the thousands of employees in offices throughout the Chicago area into one building on the western area of Chicago's Loop. They wanted an area space of 3 million square feet (279,000 m²), and predictions for future growth which caused them to need more space. Sears hired architects Skidmore, Owings & Merrill (SOM) to produce a structure to be one of the largest office buildings in the world. Their team of architect Bruce Graham and structural engineer Fazlur Khan designed the building as nine square "tubes" (each essentially a separate building), clustered in a 3×3 matrix forming a square base with 225-foot (75 m) sides.[4]

Sears and the City of Chicago approved the design, and the first steel was put in place in April 1971. The structure was completed in May 1973. Construction costs totaled approximately US$150 million at the time,[5] equivalent to $790 million in 2014.[6]

By comparison, Taipei 101, built in 2004 in Taiwan, cost around the equivalent of US$1.76 billion in 2005 dollars. Even though regulations didn't require a fire sprinkler system, the building was equipped with one from the beginning. There are about 40,000 sprinkler heads in the building. The sprinkler system cost $4 million.[7]

In February 1982, two television antennas were added to the structure. It increased its total height to 1,707 feet (520 m). The western antenna was later extended, bringing the overall height to 1,730 feet (527 m)[8] on June 5, 2000 to improve reception of local NBC.

Before the Willis Tower was completed, the tallest building in the world was the World Trade Center. In 1996, the Petronas Twin Towers in Kuala Lumpur, Malaysia became the world's tallest buildings. The Willis Tower is still the tallest building in the world from ground to pinnacle because of the antennas on top of it.

Sears executives decided that the space they would immediately occupy should be efficiently designed to house their Merchandise Group. But floor space for future growth would be rented out to smaller firms and businesses until Sears could retake it. Therefore, those floor areas had to be designed to a smaller plate, with a high window-space to floor-space ratio, to be attractive and marketable to prospective lessees.

Name rights[change | change source]

The building was soon renamed Willis Tower in July 2009 after the Willis Group bought the skyscraper. Time magazine called the name change one of the top 10 worst corporate name changes. It also pointed the negative press coverage by local news outlets and online petitions from angry residents.[2] The naming rights issue continued into 2013, when a news reporter of the Chicago Tribune said that "We're stubborn about such things. This month marked four years since the former Sears Tower was re-christened Willis Tower, and the new name has yet to stick."[9]

Design[change | change source]

The structure's design
The Willis Tower, compared to other well-known skyscrapers

Smaller floorplates required a taller structure to yield sufficient square footage. Skidmore architects proposed a tower with large 55,000-square-foot (5,000 m²) floors in the lower part of the building, and gradually tapered areas of floorplates in a series of setbacks, which would give the Sears Tower its distinctive look. The design was inspired by an advertisement for a package of cigarettes.[10]

Height[change | change source]

From the ground to the top of the taller antenna is 527 m (1,730 ft). The building leans about 4 inches (10 cm) towards the west due to its slightly asymmetrical design, placing unequal loads on its foundation. The Willis Tower is the third the tallest skyscraper in North America.[11] The building is so tall that the observatory elevators in the tower are the fastest in the world at 1600 feet (500 m) per minute, so that they can reach the sky deck faster. With clear weather, four states are viewable up to 50 miles away: Michigan, Indiana, Illinois, and Wisconsin.[12]

On November 8, 2013, a debate started between architects across Chicago and New York City debating about the height of the One World Trade Center.[13] They were saying that there was a possibility that the Willis Tower is taller than the One World Trade Center.[13] On November 12, it was confirmed that the One World Trade Center is taller than the Willis Tower.[14]

The skydeck from outside the tower

The Skydeck[change | change source]

The Sears Tower observation deck, called the Skydeck, opened on June 22, 1974. It is located on the 103rd floor of the tower. It is 1,353 feet (412 m) high and is one of the most famous tourist attractions in Chicago. Tourists can experience how the building sways on a windy day.[12] They can see far over the plains of Illinois and across Lake Michigan to Indiana, Michigan and Wisconsin on a clear day. Elevators take tourists to the top in about 60 seconds. This allows tourists to feel the pressure change as they rise up.

In January 2009, Willis Tower's owners began a major renovation of the Skydeck. They added a retractable glass balconies, extending approximately four feet from the tower. It is located on the 103rd floor. The all-glass boxes allow visitors to look through the floor to the street 1,353 feet (412 m) below. The boxes can hold up to five short tons of weight (about 4.5 metric tons). It was open to the public on July 2, 2009.[15][16]

References[change | change source]

  1. "Willis Tower - The Skyscraper Center". Council on Tall Buildings and Urban Habitat. http://skyscrapercenter.com/chicago/willis-tower/.
  2. 2.0 2.1 Suddath, Claire (February 8, 2010). "Top 10 Worst Corporate Name Changes: It's the Sears Tower". TIME. http://www.time.com/time/specials/packages/article/0,28804,1914815_1914808_1914812,00.html. Retrieved February 8, 2010.
  3. Kerch, Steve (October 20, 1991). "This job is a tall order Sears Tower project is the height of redevelopment." Chicago Tribune.
  4. "The Tallest Skyscraper", Time, Jun 11, 1973
  5. "Databank: Sears Tower", Wonders of the World, PBS Databank. Retrieved November 19, 2007.
  6. "Consumer Price Index (estimate) 1800–2008". Federal Reserve Bank of Minneapolis. http://www.minneapolisfed.org/community_education/teacher/calc/hist1800.cfm. Retrieved 2009-08-01.
  7. The Times-News, Feb 15 1975
  8. SkyscraperPage – Sears Tower. Federal Communications Commission, CTBUH
  9. Zorn, Eric (2013). "Change of Subject - 'Thillens Stadium' is no more". Chicago Tribune (The Tribune Company) (June 24, 2013). http://www.chicagotribune.com/news/local/ct-oped-0623-zorn-20130623,0,7213374.column.
  10. The History Channel; Modern Marvels (series); episode: The Sears Tower
  11. "Willis Tower history and facts". Willis Tower.com. http://www.willistower.com/building-information/history-and-facts. Retrieved December 29, 2013.
  12. 12.0 12.1 "Willis Tower Fast Facts". CNN.com. November 14, 2013. http://www.cnn.com/2013/10/03/us/willis-tower-fast-facts/index.html. Retrieved December 8, 2013.
  13. 13.0 13.1 "Willis Tower, One World Trade Center compete for bragging rights as America's tallest skyscraper". CBS News.com. http://www.cbsnews.com/8301-505263_162-57611461/willis-tower-one-world-trade-center-compete-for-bragging-rights-as-americas-tallest-skyscaper/. Retrieved November 9, 2013.
  14. "One World Trade Center taller than Willis Tower". Examiner.com. http://www.examiner.com/article/one-world-trade-center-taller-than-willis-tower. Retrieved November 12, 2013.
  15. ""Sears Tower unveils 103rd floor glass balconies"". USA Today. Jul 1, 2009. http://www.usatoday.com/travel/destinations/2009-07-01-sears-tower-glass-balconies_N.htm. Retrieved December 29, 2013.
  16. "The Ledge at Skydeck Chicago". http://www.som.com/content.cfm/sears_tower_observation_deck. SOM.com Project Page

Other pages[change | change source]

Other websites[change | change source]