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Willis Tower

Coordinates: 41°52′44″N 87°38′09″W / 41.8789°N 87.6358°W / 41.8789; -87.6358
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Willis Tower
The Willis Tower, then known as the Sears Tower, in 1998
Willis Tower is located in Chicago metropolitan area
Willis Tower
Willis Tower
Location in Chicago
Willis Tower is located in Illinois
Willis Tower
Willis Tower
Location in Illinois
Willis Tower is located in the United States
Willis Tower
Willis Tower
Location in the United States
Former namesSears Tower (1973–2009)
Record height
Tallest in the world from 1973 to 1998[I]
Preceded byWorld Trade Center
Surpassed byPetronas Towers
General information
StatusComplete
TypeOffice, observation, communication
Architectural styleInternational
Location233 S. Wacker Drive
Chicago, Illinois,
United States
Coordinates41°52′44″N 87°38′09″W / 41.8789°N 87.6358°W / 41.8789; -87.6358
Current tenantsUnited Airlines
Named forWillis Group
Sears (1973–2009)
Construction started1970; 54 years ago (1970)
Completed1973; 51 years ago (1973)
OwnerBlackstone Group[1]
Height
Architectural442.1 m (1,450 ft)[2]
Tip527 m (1,729 ft)[2]
Top floor412.7 m (1,354 ft)[2]
Technical details
Floor count108[3] (+3 basement floors), 110 floors including mechanical.
Floor area416,000 m2 (4,477,800 sq ft)[2]
Lifts/elevators104,[2] with 16 double-decker elevators, made by Westinghouse, modernized by Schindler Group
Design and construction
ArchitectSkidmore, Owings and Merrill[2]
Fazlur Rahman Khan
Bruce Graham
Main contractorMorse Diesel International
References
I. ^ Willis Tower at Emporis
[2]

The Willis Tower, formerly known as the Sears Tower, is a 108-story, 1,450-foot (442.1 m) skyscraper in Chicago, Illinois. The tower has 108 stories, though the building's owners count the main roof as 109 and the mechanical penthouse roof as 110.[4][5] When it finished costruction in 1973, it beat the World Trade Center in New York City to become the tallest building in the world. It was the tallest building in the world for twenty-five years until the Petronas Towers were built in Malaysia. It was also the tallest building in the Western Hemisphere for 41 years, until the new One World Trade Center beat it in 2013.

Willis Tower is seen as the best work of architect Fazlur Khan.[6] As of 2021, it is the third-tallest building in the United States and the Western hemisphere. It is also the 23rd-tallest in the world. Each year, more than one million people visit its observation deck, the highest in the United States. It is one of Chicago's most popular tourist places. The tower was renamed in 2009 after the Willis Group bought the tower.

The building's largest office partner is United Airlines, which moved its corporate headquarters from 77 West Wacker Drive in 2012.[7][8][9] Other major company offices in the tower include Schiff Hardin and Seyfarth Shaw.[9] Morgan Stanley moved into the tower in 2019.[9]

It was known as the Sears Tower until 2009, as it was the headquarters of retail company Sears from its opening in 1974. Many people from Chicago still call the tower by its original name.[10]

History

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Planning and construction

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The tower during its construction, 1973

In 1969, Sears, Roebuck & Co. was the largest retailer in the world, with about 350,000 employees.[11] Sears wanted to put many of its employees into one building on the western part of Chicago's Loop.[11] The company was given a location by West Chicago Loop not far from Grant Park.[11][12] Sears eventually bought the West Chicago loop location and bought 15 old buildings from 100 owners and paid $2.7 million to the city.[12][13] Sears and the city of Chicago approved the design and construction began in April 1971.[14] Sears needed 3 million square feet (280,000 m2) of office space for its planned tower. They hired architects Skidmore, Owings & Merrill (SOM).[15] Sears paid for construction of the building.[16] Architects Bruce Graham and Fazlur Khan designed the building.[15] They designed it as a nine square "tubes".[17] It was connected in a 3×3 metal wrap forming a square base with 225-foot (69 m) sides.[17] All nine tubes would rise up to the 50th floor of the building, where the northwest and southeast tubes end.[18] The northeast and southwest tubes reach the 66th floor with the north, east, and south tubes end at the 90th.[18] The last west and center tubes reach 108 floors.[12] The Sears Tower was the first building to use this design.[19] It was both cheaper and stronger. At 1,450 feet, it had more space and was higher than the Empire State Building.[19] It cost much less per unit area.[19] The system became successful in skyscraper construction and has been used in most supertall buildings.[20][21]

With the floors left over Sears decided to rent them to other companies for offices.[22] Small metal floors were added to give enough space to people working in the tower.[18] Skidmore architects proposed a tower with large, 55,000-square-foot (5,100 m2) floors in the lower part of the building.[18] They also added metal floors with many setbacks, which would give the tower its well known look.[18]

The tower passed the height of New York's unfinished World Trade Center to become the world's tallest building.[23] The height was limited by the Federal Aviation Administration (FAA) to protect air traffic.[24] Two antennas were added at the top of the building for television and radio broadcasting.[25] The building was completed in May 1973 and opened the next year.[14] Construction cost about US$150 million.[26]

Black bands appear on the tower around the 29th–32nd, 64th–65th, 88th–89th, and 104th–108th floors.[27] These give the building's environmental support systems and hide its belted trusses.[27] Even though adding a fire sprinkler system was not forced, the building was built with one from the beginning.[28] There are around 40,000 sprinkler heads in the building. They cost $4 million.[29]

In February 1982, two television antennas were added to the building, increasing its total height to 1,707 feet (520.3 m).[25] The western antenna was made bigger, bringing the overall height to 1,729 feet (527 m) on June 5, 2000.[2] It was done to improve reception of local NBC station WMAQ-TV.[25]

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As the construction of the building reached as the 50th floor in 1972, people sued Sears and wanted to stop the building from passing 67 floors.[30] The lawsuits said that above the 67th floor would make television signals bad.[31]

The Illinois Citizens' Committee for Broadcasting wanted the Federal Communications Commission (FCC) to stop the building from getting taller.[32] On May 26, 1972, the Commission did not take action as they did not have the power to do anything.[32] On June 30, 1972, the Illinois Supreme Court supported their decision.[32] On September 8, 1972, the United States Court of Appeals for the Seventh Circuit supported the FCC decision, ending the lawsuit.[32]

After opening

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The tower did not have as many companies buying office spaces and it was half-empty for many years.[33][34] In the 2000s, many companies in the tower began to leave because of terrorist threats or because they found better office spaces.[34]

The tower seen from Lake Michigan

In 1984, Sears decided to improve the appearance of the lower floors for civilians and tourists.[35] Their solution was to create a new entrance, which became known as "Lunchbox Entrance".[35][36] Sears wanted to sell the building in the late 1980s.[34] In July 1990, with no possible buyers, Sears took out a mortgage loan on the tower for $850 million from MetLife and AEW Capital Management.[37] Sears talked about the loan again in 1994.[37] This led to an agreement where Sears would no longer be responsible for the $850 million loan, although it would only own the name of the building.[37] As part of the 1994 agreement, AEW and Metlife would own the building in 2003.[38]

In 1990, the law firm of Keck, Mahin & Cate wanted to move away from the tower and into 77 West Wacker Drive.[39] Just two years later, Sears began to move out of the tower to Hoffman Estates, Illinois.[38]

The tower seen from the Chicago River

However, in 1997, the Canadian company TrizecHahn bought AEW's holdings of the building for $110 million.[40][41] After the September 11 attacks, two of the largest office partners, Goldman Sachs and Merrill Lynch, quickly announced plans leave the building's 300,000 ft2 space.[42] In 2003, Trizec sold its holdings of the tower to MetLife for $9 million.[43]

In 2004, MetLife sold the building to a group of investors from New York City and Skokie, Illinois.[44] The price was $840 million, with $825 million held in a mortgage.[45]

In June 2006, seven men were arrested by the FBI and charged with plans to destroy the tower.[46][47] The case went to court in October 2007.[48] After three trials, five of the suspects were convicted and two acquitted.[49] The leader of the group, Narseal Batiste, was sentenced to 13.5 years in prison.[50] In response to the possible threat of an attack, the building's largest company space at this time, Ernst & Young, moved to North Wacker Drive in early 2009.[51]

Since 2007, the owners had thought about building a hotel on the north side of the building.[52] The second building was thought about in the original design.[52] The plan was eventually cancelled as the city did not allow the construction of a tall building in that location.[52]

In February 2009, the owners announced they were thinking about painting the building silver, an idea that was later stopped.[53] It was hoped that a new paint-job would "rebrand" the building and show its energy efficiency for a cost of $50 million.[53]

In 2015, the Blackstone Group bought the tower for a reported $1.3 billion, the highest price ever paid for a U.S. property outside of New York City.[54] In 2017, Blackstone announced a $500 million renovation for the building, such as building a six-story commercial area in the tower's plaza area.[55]

In May 2020, after many days of raining, the building's three basement levels were flooded.[56] This caused the power to go out and many television and radio stations going off the air.[56]

Naming rights

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The tower's entrance

Sears' naming rights ended in 2003, but the building was still called the Sears Tower for many years.[37] In March 2009, the British insurance company Willis Group Holdings agreed to rent a part of the building and got the naming rights.[57] On July 16, 2009, the building was officially renamed the Willis Tower.[58] On August 13, 2012, United Airlines said they were moving its corporate headquarters from 77 West Wacker Drive to Willis Tower.[7]

The naming rights are legally kept for 15 years, making it is possible that the building's name change again soon.[59] Many Chicagoans still call the tower by its old name.[60] A July 2009 CNN article showed some Chicagoans did not want to call the tower by its new name.[61] An October 2010 article from Chicago magazine called the building one of Chicago's 40 most important things.[62] The author of the article did not want call it the "Willis Tower".[62] Time magazine called the name change one of the top 10 worst corporate name changes.[63]

Climbing

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On May 25, 1981, Dan Goodwin climbed the tower while using suction cups and wearing a Spider-Man costume.[64] The Chicago Fire Department tried to stop him, but he made the first successful outside climb of the tower.[64] Goodwin was arrested at the top after the seven-hour climb and was later charged with trespassing.[65][66]

In August 1999, Alain "Spiderman" Robert climbed the building all the way to the top using only his hands and feet.[67] Bad weather such as fog made the last 20 stories of the building hard to climb for him.[67]

Since 2009, the Willis Tower has hosted SkyRise Chicago, the world's tallest indoor stair climb as a charity event.[68] At the event, people can legally walk up the building's 103-story staircase.[68]

Details and height

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The structure's design

Skidmore architects designed the Willis Tower to have large floors of 55,000 square feet (5,100 square meters) in the lower part of the building.[15] They got the design idea from an advertisement for a package of cigarettes.[69]

From the ground to the top of the taller antenna, Willis Tower is 1,729 feet (527 meters) tall.[15][69] It leans about 4 inches (10 centimeters) towards the west because of unequal weight on its foundation.[70] The observation deck elevators are the fastest in the world at 1,600 feet (490 meters) per minute.[71] With clear weather, four states can be seen from the observation deck: Michigan, Indiana, Illinois, and Wisconsin.[72]

The Willis Tower is the third tallest building in the Americas (after One World Trade Center and Central Park Tower) and the Western Hemisphere.[73] With a height of 1,729 feet (527 m) with its antenna, it is the third-tallest freestanding structure in the Americas and eighth-tallest freestanding structure in the world.[74]

On November 8, 2013, architects in Chicago and New York City started talking about the height of the One World Trade Center.[75] They were saying that Willis Tower might be taller.[75] Four days later, it was made official that One World Trade Center is taller than the Willis Tower.[76]

At the bottom, the lowest level of Willis Tower is 43 feet below elevation.[77] Many broadcast station transmitters are built at the top of Willis Tower.[25]

The Skydeck

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The tower's glass ledge on its skydeck

The Willis Tower observation deck is called the Skydeck.[74] It opened on June 22, 1974.[74] It is on the 103rd floor.[74] It is the highest observation deck in the United States and one of Chicago's most famous tourist attractions.[74][78] About 1.7 million tourists visit the tower every year.[74] Elevators reach the top of the building in about 60 seconds.[71] People can feel the air pressure change as they go up.[71] The tourist entrance is on the south side of the building on Jackson Boulevard.[79] A second observation deck on the 99th floor was made as a backup and for private events.[80][81]

In January 2009, work to improve the Skydeck began, such as adding glass balconies that go 4 feet (1.2 m) outside of the building.[82] The all-glass boxes are called "The Ledge." Visitors can see the street below.[82] The boxes can hold 5 short tons (4.5 metric tons).[82] It opened to the public on July 2, 2009.[82] On May 29, 2014, the laminated glass flooring of one of the boxes broke while visitors were inside. Nobody was hurt.[83] The flooring on that same box cracked on June 12, 2019.[84]

Awards

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The U.S. Environmental Protection Agency (EPA) gave the tower ENERGY STAR certification in 2018 for good energy efficiency.[85]

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References

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  1. ↑ de la Merced, Michael J. (March 16, 2014). "Blackstone Group Purchases Landmark Willis Tower in Chicago". The New York Times. Archived from the original on October 27, 2015. Retrieved August 11, 2015.
  2. ↑ 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 "Willis Tower – The Skyscraper Center". Council on Tall Buildings and Urban Habitat. June 13, 2015. Archived from the original on December 23, 2019. Retrieved June 13, 2015.
  3. ↑ 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. Emporis.com Archived 2008-03-17 at the Wayback Machine Retrieved on June 7, 2008
  4. ↑ "Willis Tower - The Skyscraper Center". www.skyscrapercenter.com. Archived from the original on 2021-01-28. Retrieved 2021-01-20.
  5. ↑ "History and Facts - Willis Tower". willistower.com. Archived from the original on 2021-07-22. Retrieved 2021-07-27.
  6. ↑ "Five things you need to know about pioneering architect Fazlur Rahman Khan". The Independent. London. April 3, 2017. Archived from the original on April 4, 2020. Retrieved July 27, 2021.
  7. ↑ 7.0 7.1 [1] Archived August 15, 2012, at the Wayback Machine
  8. ↑ Snyder, Brett (December 16, 2013). "A Day with United Management: Elite Status, Mileage Devaluation, and Increasing Change Fees". The Cranky Flier. Archived from the original on December 19, 2013. Retrieved December 18, 2013.
  9. ↑ 9.0 9.1 9.2 Ecker, Danny (2018-04-16). "Morgan Stanley moving second office to Willis Tower". Crain's Chicago Business. Archived from the original on 2018-10-04. Retrieved 2018-10-03.
  10. ↑ McClelland, Edward (2019-06-05). "Chicagoans Refuse to Call These Places by Their Real Names". Chicago Magazine. Chicago Magazine. Archived from the original on 2021-05-19. Retrieved 2021-05-19.
  11. ↑ 11.0 11.1 11.2 "Sears & Roebuck through the years: From watches to catalogs to Kmart to bankruptcy". Pennlive. 14 January 2019. Archived from the original on July 27, 2021. Retrieved July 27, 2021.
  12. ↑ 12.0 12.1 12.2 "CHICAGO NEIGHBORHOODS: WEST LOOP". The Skydeck. Archived from the original on July 27, 2021. Retrieved July 27, 2021.
  13. ↑ "14 Things You Might Not Know About the Sears/Willis Tower". Mental Floss. 25 August 2015. Archived from the original on July 27, 2021. Retrieved July 27, 2021.
  14. ↑ 14.0 14.1 "Sears Tower is Completed". Famous Daily. Archived from the original on April 11, 2021. Retrieved July 27, 2021.
  15. ↑ 15.0 15.1 15.2 15.3 "WILLIS TOWER (FORMERLY SEARS TOWER)". SOM. Archived from the original on July 27, 2021. Retrieved July 27, 2021.
  16. ↑ "JAPANESE STEER CLEAR OF SEARS TOWER SALE". Chicago Tribune. June 29, 1989. Archived from the original on November 9, 2021. Retrieved July 27, 2021.
  17. ↑ 17.0 17.1 "The Tallest Skyscraper". Time. June 11, 1973. Archived from the original on 2008-03-08. Retrieved July 26, 2021.
  18. ↑ 18.0 18.1 18.2 18.3 18.4 "Willis Tower". Architecture. Archived from the original on July 27, 2021. Retrieved July 27, 2021.
  19. ↑ 19.0 19.1 19.2 National Academy of Engineering (1979). Memorial Tributes. National Academies. ISBN 9780309034821. NAP:14723. Archived from the original on 2021-07-27. Retrieved 2021-07-27.
  20. ↑ "Burj Dubai: The new pinnacle of vanity". Telegraph. Archived from the original on May 31, 2019. Retrieved February 25, 2014.
  21. ↑ "Top 10 world's tallest steel buildings". Constructionweekonline.com. Archived from the original on March 28, 2014. Retrieved February 25, 2014.
  22. ↑ "AN AMERICAN ICON WITH A RICH HISTORY". Willis Tower. Archived from the original on July 22, 2021. Retrieved July 27, 2021.
  23. ↑ McGeehan, Patrick (12 November 2013). "One World Trade Center is Ruled Tallest Building in the U.S." The New York Times. Archived from the original on July 27, 2021. Retrieved July 27, 2021.
  24. ↑ "The world's tallest buildings aren't being built in the USA anymore". USA Today. Archived from the original on July 27, 2021. Retrieved July 27, 2021.
  25. ↑ 25.0 25.1 25.2 25.3 "A BEACON FOR THE WORLD TO SEE". Willis Tower. Archived from the original on July 27, 2021. Retrieved July 27, 2021.
  26. ↑ "Databank: Sears Tower". Wonders of the World. November 19, 2007. Archived from the original on November 6, 2011. Retrieved July 26, 2021.
  27. ↑ 27.0 27.1 "Willis Tower". Britannica. Archived from the original on July 31, 2020. Retrieved July 27, 2021.
  28. ↑ "The Chicago Tragedy". Fire Engineering. December 2003. Archived from the original on July 27, 2021. Retrieved July 27, 2021.
  29. ↑ "Sears Tower's Price Tag Seen Topping $1 Billion". Los Angeles Times. November 1988. Archived from the original on 2021-07-27. Retrieved July 27, 2021.
  30. ↑ "The Forgotten History Of Chicago Supertalls: Everything You Need To Know About Willis Tower". Bisnow. Archived from the original on July 27, 2021. Retrieved July 27, 2021.
  31. ↑ "December 2, 1973: Chicago Tribune from Chicago, Illinois · Page 740". Newspapers. Archived from the original on July 27, 2021. Retrieved July 27, 2021.
  32. ↑ 32.0 32.1 32.2 32.3 "Illinois Citizens Committee for Broadcasting v. Federal Communications Commission". Case Text. Archived from the original on July 27, 2021. Retrieved July 27, 2021.
  33. ↑ Holusha, John (22 January 1995). "Technology; The Sears Tower Challenge". The New York Times. Archived from the original on July 27, 2021. Retrieved July 27, 2021.
  34. ↑ 34.0 34.1 34.2 "Sears Tower: Tall Bill to Fill". Chicago Tribune. Archived from the original on 2021-11-09. Retrieved July 27, 2021.
  35. ↑ 35.0 35.1 "New Amenities for World's Tallest Building". The New York Times. 8 April 1984. Archived from the original on July 27, 2021. Retrieved July 27, 2021.
  36. ↑ "Willis Tower says goodbye to its 'lunchbox' entrance along Wacker Drive". Chicago Curbed. 6 April 2018. Archived from the original on 30 July 2021. Retrieved 30 July 2021.
  37. ↑ 37.0 37.1 37.2 37.3 "Sears Tower likely to go to its lender". Chicago Tribune. Archived from the original on 2021-07-12. Retrieved July 27, 2021.
  38. ↑ 38.0 38.1 "A CASE STUDY OF THE DEVELOPMENT, RE-FINANCINGS AND SALE OF NORTH AMERICA'S TALLEST BUILDING" (PDF). tribunedigital-chicagotribune. Archived from the original on 2021-11-09. Retrieved 2018-02-09.
  39. ↑ "77 W. Wacker ready to go". Chicago Sun-Times. March 12, 1990. Archived from the original on 2012-11-02. Retrieved July 26, 2021.
  40. ↑ Vinocur, Barry (December 8, 1997). "A Look at the Finer Points of the Sears Tower Sale". Barron's. Archived from the original on April 30, 2021. Retrieved July 27, 2021.
  41. ↑ "Sears Tower may be for sale". Crains Chicago Business. October 31, 1997. Archived from the original on 2001-12-14. Retrieved July 26, 2021.
  42. ↑ "Merrill Lynch moving most of its offices out of Sears Tower". Chicago Tribune. Archived from the original on 2021-11-09. Retrieved July 27, 2021.
  43. ↑ "Trizec to sell its last local asset". Crain's Chicago Business. September 27, 2006. Archived from the original on 2001-12-14. Retrieved July 26, 2021.
  44. ↑ "BIZ BRIEFS". Chicago Sun-Times. May 1, 2004. Archived from the original on 2012-10-26. Retrieved July 26, 2021.
  45. ↑ "MetLife to Complete Sale of Chicago's Sears Tower". Chicago Tribune. April 30, 2004. Archived from the original on 2012-10-26. Retrieved July 26, 2021.
  46. ↑ "FBI Killed Plot in Talking Stage". The New York Times. June 24, 2006. Archived from the original on July 27, 2021. Retrieved July 26, 2021.
  47. ↑ "Seven charged over 'Chicago plot'". BBC News. June 23, 2006. Archived from the original on July 27, 2021. Retrieved July 26, 2021.
  48. ↑ "Sears Tower 'plot trial' begins". BBC News. October 3, 2007. Archived from the original on July 27, 2021. Retrieved July 26, 2021.
  49. ↑ "Five guilty in Chicago bomb plot". BBC News. May 12, 2009. Archived from the original on July 27, 2021. Retrieved July 26, 2021.
  50. ↑ "Sears Tower bomb plot leader Narseal Batiste jailed". BBC News. November 20, 2009. Archived from the original on July 27, 2021. Retrieved July 26, 2021.
  51. ↑ "Sears Tower to Lose Largest Tenant - The Chicago 77". www.thechicago77.com. 9 January 2009. Archived from the original on 2018-10-04. Retrieved 2018-10-03.
  52. ↑ 52.0 52.1 52.2 "Tall order for Tower? Sears Tower owners to press city for zoning change, subsidy to add 2nd building as part of mega-million-dollar project next to landmark". Chicago Sun-Times. October 12, 2007. Archived from the original on 2012-11-02. Retrieved July 26, 2021.
  53. ↑ 53.0 53.1 "Sears Tower in silver?". Chicago Sun-Times. February 25, 2009. Archived from the original on February 17, 2010.
  54. ↑ "Subscription Center". 4 June 2015. Archived from the original on 2017-01-13. Retrieved 2021-07-27.
  55. ↑ "Willis Tower in line for a $500 million facelift". Chicago Sun-Times. Archived from the original on 2018-10-04. Retrieved 2018-10-03.
  56. ↑ 56.0 56.1 "Flooding at Willis Tower knocks TV, radio signals off the air". May 20, 2020. Archived from the original on August 2, 2021. Retrieved August 2, 2021.
  57. ↑ "Sears Tower Being Renamed". Chicago Breaking News. March 12, 2009. Archived from the original on March 16, 2009. Retrieved July 26, 2021.
  58. ↑ "Tallest Building in Western Hemisphere is Renamed Willis Tower". Willis Group. July 16, 2009. Archived from the original on June 13, 2015. Retrieved June 13, 2015.
  59. ↑ Burns, Greg (July 16, 2009). "Burns on Business, Willis Wants to be Part of Chicago by Way of Jersey". Chicago Tribune. Archived from the original on July 3, 2012. Retrieved July 16, 2009.
  60. ↑ Podmolik, Mary Ellen (2009). "Sears Tower name change has few Chicago fans – Willis Tower may have trouble winning over public". Chicago Tribune (March 13, 2009). Archived from the original on March 14, 2014. Retrieved July 27, 2021.
  61. ↑ "Sears Tower Now Named Willis Tower". CNN. July 16, 2009. Archived from the original on July 19, 2009. Retrieved July 17, 2009.
  62. ↑ 62.0 62.1 Johnson, Geoffrey (2010). "Top 40 Buildings in Chicago". Chicago (October 2010). Archived from the original on 2018-12-24. Retrieved 2021-07-27.
  63. ↑ Suddath, Claire (February 8, 2010). "Top 10 Worst Corporate Name Changes: It's the Sears Tower". TIME. Archived from the original on February 22, 2010. Retrieved February 8, 2010.
  64. ↑ 64.0 64.1 "Sears Tower in Chicago Is Scaled by Stunt Man". New York Times. May 26, 1981. Archived from the original on February 18, 2008. Retrieved October 31, 2011.
  65. ↑ "Chicago Cubs History and News – Welcome to Just One Bad Century". Justonebadcentury.com. Archived from the original on March 20, 2012. Retrieved October 31, 2011.
  66. ↑ "Spiderman scales Sears Tower w/Stan Lee interview". YouTube. Archived from the original on April 2, 2014. Retrieved January 13, 2009.
  67. ↑ 67.0 67.1 "'Spiderman' scales Sears Tower in Chicago – August 20, 1999". CNN. Archived from the original on July 1, 2009. Retrieved September 14, 2009.
  68. ↑ 68.0 68.1 Pathieu, Diane (4 November 2019). "Hundreds of stair climbers reach new heights for annual SkyRise Chicago at Willis Tower". ABC 7 Chicago. Archived from the original on 5 November 2019. Retrieved 10 May 2020.
  69. ↑ 69.0 69.1 "Willis Tower". PBS. 21 October 2011. Archived from the original on July 27, 2021. Retrieved July 27, 2021.
  70. ↑ "Interesting Facts About the Sears Tower". JFF. 30 October 2016. Archived from the original on July 27, 2021. Retrieved July 27, 2021.
  71. ↑ 71.0 71.1 71.2 "Elevator Modernization". Willis Tower. Archived from the original on July 27, 2021. Retrieved July 27, 2021.
  72. ↑ "Willis Tower Fast Facts". CNN.com. November 14, 2013. Retrieved December 8, 2013.
  73. ↑ "SOM completes overhaul of Chicago tower, formerly tallest building in the world". Global Construction Review. 27 April 2021. Archived from the original on July 27, 2021. Retrieved July 27, 2021.
  74. ↑ 74.0 74.1 74.2 74.3 74.4 74.5 "DARE TO STAND OUT". Skydeck. Archived from the original on July 27, 2021. Retrieved July 27, 2021.
  75. ↑ 75.0 75.1 "Willis Tower, One World Trade Center compete for bragging rights as America's tallest skyscraper". CBS News.com. Archived from the original on November 8, 2013. Retrieved November 9, 2013.
  76. ↑ "One World Trade Center taller than Willis Tower". Examiner.com. Archived from the original on October 31, 2015. Retrieved November 12, 2013.
  77. ↑ "Willis Tower Fun Facts | Fun Facts for Children". Skydeck Chicago. Archived from the original on 2020-10-23. Retrieved 2020-11-08.
  78. ↑ "Skydeck Chicago - The Ledge". Enjoy Illinois. Archived from the original on July 27, 2021. Retrieved July 27, 2021.
  79. ↑ "Directions to the Skydeck". The Sky Deck. Archived from the original on July 27, 2021. Retrieved July 27, 2021.
  80. ↑ "THE HOWS, WHATS AND WOWS OF THE WILLIS TOWER" (PDF). The Sky Deck. Archived (PDF) from the original on May 13, 2014. Retrieved July 27, 2021.
  81. ↑ "THE ULTIMATE CHICAGO EVENT VENUE: WILLIS TOWER'S 99TH FLOOR". The Skydeck. Archived from the original on July 30, 2021. Retrieved July 30, 2021.
  82. ↑ 82.0 82.1 82.2 82.3 "Sears Tower unveils 103rd floor glass balconies". USA Today. July 1, 2009. Archived from the original on July 24, 2012. Retrieved July 26, 2021.
  83. ↑ BJ Lutz (May 30, 2014). "Coating on Willis Tower Skydeck's Ledge Cracks Under Tourists". Nbcchicago.com. Archived from the original on June 15, 2019. Retrieved August 26, 2014.
  84. ↑ Sophie Lewis (June 12, 2019). "Protective layer of Willis Tower's SkyDeck cracks under visitors' feet". cbsnews. Archived from the original on June 13, 2019. Retrieved June 12, 2019.
  85. ↑ "WILLIS TOWER EARNS EPA'S ENERGY STAR® CERTIFICATION FOR SUPERIOR ENERGY EFFICIENCY". Willis Tower. Archived from the original on July 27, 2021. Retrieved July 27, 2021.

Other websites

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