Willis Tower

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Willis Tower
Willis Tower was the world's tallest building from 1974 to 1998.[I]
Former/other names	Sears Tower
Record height
Preceded by	World Trade Center
Surpassed by	Petronas Twin Towers
General information
Location	233 S. Wacker Drive Chicago, Illinois 60606 United States
Coordinates	41°52′44″N 87°38′09″WCoordinates: 41°52′44″N 87°38′09″W
Status	Complete
Constructed	1970-1973
Use	Office, observation, communication
Height
Antenna or spire	1,730 feet (527 m)
Roof	1,451 ft (442 m)[1]
Technical details
Floor count	108[1]
Floor area	4.56 million sq ft (3.81 million sq ft rentable) 424,000 m² (354,000 m² rentable)[2]
Elevators	104, with 16 double-decker elevators, made by Westinghouse, modernized by Schindler Group
Companies involved
Architect(s)	Skidmore, Owings and Merrill
^ Fully habitable, self-supported, from main entrance to highest structural or architectural top; see the list of tallest buildings in the world for other listings.

Willis Tower, formerly named Sears Tower, is a 108-story, 1451-foot (442 m) skyscraper in Chicago, Illinois.^[1] At the time of its completion in 1974, it was the tallest building in the world, surpassing the World Trade Center towers in New York, and it held this rank for nearly 25 years. The Willis Tower is the tallest building in the United States and the fifth-tallest freestanding structure in the world, as well as the fifth tallest building in the world to the roof.
Although Sears' naming rights expired in 2003, the building continued to be called Sears Tower for several years. In March 2009 London-based insurance broker Willis Group Holdings, Ltd., agreed to lease a portion of the building and obtained the building's naming rights.^[3] On July 16, 2009, the building was officially renamed Willis Tower.

Contents [hide] 1 History 1.1 Planning and construction 1.2 Post-opening 2 Plans 3 The Skydeck 4 Height 5 Naming rights 6 Cultural depictions 6.1 Film and television 6.2 Other 7 Position in Chicago's skyline 8 Figures and statistics 9 Broadcasting 9.1 Radio stations 9.2 Television stations 10 Gallery 11 See also 12 References 13 External links

History

Planning and construction

In 1969, Sears, Roebuck & Co. was the largest retailer in the world, with approximately 350,000 employees.^[4] Sears executives decided to consolidate the thousands of employees in offices distributed throughout the Chicago area into one building on the western edge of Chicago's Loop. With immediate space demands of 3 million square feet (279,000 m²), and predictions for future growth necessitating more space, Sears commissioned architects Skidmore, Owings and 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 3x3 matrix.^[5] All nine tubes would rise up to the 50th floor of the building. At the 50th floor, the northwest and southeast tubes end, and the remaining seven continue up. At the 66th floor, the northeast and the southwest tubes end. At the 90th floor, the north, east, and south tubes end. The remaining west and center tubes continue up to the 108th floor.
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. 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.
As Sears continued to offer optimistic projections for growth, the tower's proposed height soared into the low hundreds of floors and surpassed the height of New York's unfinished World Trade Center to become the world's tallest building. Restricted in height by a limit imposed by the Federal Aviation Administration (FAA) to protect air traffic, the Sears Tower was financed by the company. It was topped with two antennas to permit local television and radio broadcasts. 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 $150 million USD at the time,^[6] which would be equivalent to roughly $950 million USD in 2005. By comparison, Taipei 101, built in 2004 in Taiwan, cost around the equivalent of US$1.76 billion in 2005 dollars.
Black bands appear on the tower around the 29th–32nd, 64th–65th, 88th–89th, and 104th–108th floors. These are louvers which allow ventilation for service equipment and obscure the structure's belt trusses.
In February 1982, two television antennas were added to the structure, increasing its total height to 1,707 feet (520 m). The western antenna was later extended to 1,730 feet (527 m)^[7] on June 5, 2000 to improve reception of local NBC station WMAQ-TV.

Post-opening

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Willis Tower by night, seen from the Loop.

Willis Tower from across the Chicago River

Sears' optimistic growth projections were not met. Competition from its traditional rivals (like Montgomery Ward) continued, with new competition by retailing giants such as Kmart, Kohl's, and Wal-Mart. The fortunes of Sears & Roebuck declined in the 1970s as the company lost market share; its management grew more cautious.^[8] The Sears Tower was not the draw Sears had hoped it would be. The tower stood half-vacant for a decade as a surplus of office space was erected in Chicago in the 1980s.
By 1990, Keck, Mahin & Cate, a law firm, considered moving out of its space in the Sears Tower and moving into a potential new development, which would become 77 West Wacker Drive. Brokers who were familiar with the lease negotiations stated that Sears was trying to keep Keck, Mahin & Cate in the building. Keck, Mahin & Cate decided to move into 77 West Wacker, and the Prime Group, developer of 77 West Wacker, finalized the development of the facility. During the time that Keck, Mahin & Cate was scheduled to move out of the Sears Tower, Sears planned to move its offices to its merchandise group facilities in Hoffman Estates, Illinois.^[9] Sears began moving its offices out of the Sears Tower in 1992.^{[citation needed]}
In 1994 Sears sold the building to Boston-based AEW Capital Management with financing from MetLife. At the time it was one third vacant. By 1995 Sears had completely vacated the building, moving to a new office campus in Hoffman Estates.^{[citation needed]}
In 1997 Toronto-based TrizecHahn Corp (the owner at the time of the CN Tower) purchased the building for $110 million, and assumption of $4 million in liabilities, and a $734 million mortgage.^[10][11] In 2003 Trizec surrendered the building to lender MetLife.^[12]
In 2004 MetLife sold the building to a group of investors, including New York-based Joseph Chetrit, Joseph Moinian, Lloyd Goldman, Joseph Cayre and Jeffrey Feil, and Skokie-based American Landmark Properties.^[13] The quoted price was $840 million, with $825 million held in a mortgage.^[14]
In June 2006, seven men were arrested by the FBI and charged with plotting to destroy the tower. Deputy FBI Director John Pistole described their plot as "more aspirational than operational."^[15][16] The case went to court in October 2007;^[17] after three trials, five of the suspects were convicted and two were acquitted.^[18] The alleged leader of the group, Narseal Batiste, was sentenced to 13½ years in prison in November 2009.^[19]

Plans

In February 2009, the owners announced they were considering a plan to paint the structure silver. The paint would "rebrand" the building and highlight its advances in energy efficiency. The estimated cost is $50 million.^[20]
Since 2007, the building owners have been considering building a hotel on the north side of Jackson, between Wacker and Franklin, at the plaza that is the entrance to the tower's observation deck. The tower's parking garage is beneath the plaza. Building owners say the second building was considered in the original design. City zoning does not permit construction of such a tall tower there.^[21]

The Skydeck

Three glass bottom skyboxes (top right) on the east facade of the Willis Tower at the 103rd floor , seen from street level.

The Sears Tower observation deck, called the Skydeck, opened on June 22, 1974. Located on the 103rd floor of the tower, it is 1,353 feet (412 m) above ground and is one of the most famous tourist attractions in Chicago. Tourists can experience how the building sways on a windy day. 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. The Skydeck competes with the John Hancock Center's observation floor a mile and a half away, which is 323 feet (98 m) lower. Some 1.3 million tourists visit the Skydeck annually. A second Skydeck on the 99th floor is used when the 103rd floor is closed. The tourist entrance can be found on the south side of the building along Jackson Boulevard.
In January 2009, the Willis Tower owners began a major renovation of the Skydeck, to include the installation of glass balconies, extending approximately four feet over Wacker Drive from 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, which can bear five short tons of weight (about 4.5 metric tons), opened to the public on July 2, 2009.^[22][23]
In August 1999 French urban climber Alain "Spiderman" Robert, using only his bare hands and feet, scaled the building's exterior glass and steel wall all the way to the top. A thick fog settled in near the end of his climb, making the last 20 floors of the building's glass and steel slippery.^[24]
The building's official address is 233 South Wacker Drive, Chicago, Illinois 60606.

Height

• Burj Khalifa, Dubai
• CN Tower, Toronto
• Willis Tower, Chicago

Willis Tower remains the tallest building in the Americas. With a pinnacle height of 1730 feet (527 m), it is the second tallest freestanding structure in the Americas, as it is 86 feet (26 m) shorter than Toronto's CN Tower, and is the only other freestanding structure in the Americas to exceed 1500 feet (457.2 m) in height. As of August 2009, Willis Tower is the fifth tallest freestanding structure in the world (by pinnacle height), after the Burj Khalifa, the Canton Tower, the CN Tower and the Ostankino Tower.
At 1,482.6 feet (451.9 m) tall, including decorative spires, the Petronas Twin Towers in Kuala Lumpur, Malaysia, laid claim to replacing the Sears Tower as the tallest building in the world in 1998. Not everyone agreed, and in the ensuing controversy four different categories of "tallest building" were created. Of these, Petronas was the tallest in one category (height to top of architectural elements, meaning spires but not antennas).
Taipei 101 in Taiwan claimed the record in three of the four categories in 2004 to become generally recognized as the tallest building in the world. Taipei 101 surpassed the Petronas Twin Towers in spire height and the Sears Tower in roof height; it also claimed the record for highest occupied floor. The Sears Tower retained one record: its antenna exceeded the Taipei 101's spire in height. In 2008, the Shanghai World Financial Center claimed the records of tallest building by roof and highest occupied floor.
On August 12, 2007, the Burj Khalifa in Dubai, United Arab Emirates was reported by its developers to have surpassed the Sears Tower in all height categories.^[25]
When completed, One World Trade Center in New York City is expected to surpass Willis Tower through its structural and pinnacle heights, but not by roof or highest occupied floor.^[26] Burj Khalifa currently holds (by a significant margin) all height records, surpassing the Sears Tower, the CN Tower, One World Trade Center, Taipei 101 and Shanghai World Financial Center in every category. The Chicago Spire, which has a planned height of 610 m (2,000 ft) is expected to lay claim to all categories of height records in the Americas upon completion, but its construction is currently on hold due to financial difficulties.^[27]
Until 2000, the Sears Tower did not hold the record for the tallest building by pinnacle height. From 1969 to 1978, this record was held by the John Hancock Center, whose antenna reached a height of 1,500 ft (457.2 m), or 49 ft (14.8 m) taller than the Sears Tower's original height of 1,451 ft (442 m). In 1978, One World Trade Center became taller by pinnacle height due to the addition of a 359 ft (109.3 m) antenna, which brought its total height to 1,727 ft (526.8 m). In 1982, two antennas were installed on top of the Sears Tower which brought its total height to 1,707 ft (520.3 m), making it taller than the John Hancock Center but not One World Trade Center. However, the extension of the Sears Tower's western antenna in June 2000 to 1,730 feet (527 m) allowed it to just barely claim the title of tallest building by pinnacle height.

Naming rights

West facade and entrance.

Although Sears sold the Tower in 1994 and had completely vacated it by 1995, the company retained the naming rights to the building through 2003. The new owners were rebuffed in renaming deals with CDW Corp in 2005 and the U.S. Olympic Committee in 2008. London-based insurance broker Willis Group Holdings, Ltd. leased more than 140,000 square feet (13,000 m²) of space on three floors in 2009. A Willis spokesman said the naming rights were obtained as part of the negotiations at no cost to Willis,^[28][29][30] and the building was renamed Willis Tower on July 16, 2009.^[31] The naming rights are valid for 15 years so it is possible that the building’s name could change again in 2024.^[32] The Chicago Tribune joked that the building’s new name reminded them of the oft-repeated "What you talkin' 'bout, Willis?" catchphrase from the 1980s American television sitcom Diff'rent Strokes^[31] and considered the name-change ill-advised in "a city with a deep appreciation of tradition and a healthy ego, where some Chicagoans still mourn the switch from Marshall Field's to Macy's.^[33] This feeling was confirmed in a July 16, 2009 CNN article in which some Chicago area residents expressed reluctance to accept the Willis Tower name,^[34] and in an article that appeared in the October, 2010 issue of Chicago magazine that ranked the building among Chicago's 40 most important, the author pointedly refused to acknowledge the name change and referred to the building as "Sears Tower".^[35] Time magazine called the name change one of the top 10 worst corporate name changes and pointed to negative press coverage by local news outlets and online petitions from angry residents.^[36]

Cultural depictions

Willis Tower as viewed from Chicago Chinatown

Film and television

The building has appeared in numerous films and television shows set in Chicago such as Ferris Bueller's Day Off, where Ferris and company watch the streets of Chicago from the observation deck.^[37] The television show Late Night with Conan O'Brien introduced a character called The Sears Tower Dressed In Sears Clothing when the show visited Chicago in 2006.^[38] The building is also featured in History Channel's Life After People, in which it and other human-made landmarks suffer from neglect without humans around, and it collapses two hundred years after people are gone.^[39] In an episode of the television series, Monk, Adrian Monk tries to conquer his fear of heights by imagining that he is on top of the Sears Tower. Also, in an episode of Kenan and Kel, Kenan Rockmore and Kel Kimble decide to climb to the top of the Sears Tower, so that Kenan can declare his love for a girl.
On May 25, 1981, Dan Goodwin, wearing a homemade Spider-Man suit while using suction cups, camming devices, and sky hooks, and despite several attempts by the Chicago Fire Department to stop him, made the first successful outside ascent of Sears Tower. Goodwin was arrested at the top after the seven hour climb and charged with trespassing. Goodwin stated the reason he made the climb was to call attention to shortcomings in high-rise rescue and firefighting techniques. After a lengthy interrogation by Chicago's District Attorney and Fire Commissioner, Goodwin was released.^{[40][41][42][43]}
In the movie Category 6: Day of Destruction, the tower is damaged by a tornado.
In "1969", a Season 2 episode of the science-fiction series Stargate SG-1, the SG1 team accidentally travels back in time to the titular year. At one point, the team travels though Chicago and the Sears Tower is shown (erroneously, since construction did not begin on the tower until two years later in 1971).
In the movie I, Robot, the tower is shown updated in the year 2035 with new red antennas.

Other

Older versions of Microsoft Flight Simulator would begin with the player on the runway of Meigs Field, facing a virtual version of the tower.

Position in Chicago's skyline

Figures and statistics

• The top of Willis Tower is the highest point in Illinois. The tip of its highest antenna is 1,730 feet (527.3 m) above street level or 2,325 feet (708 m) above sea level, its roof is 1,450 feet 7 inches (442.14 m) above street level or 2,046 feet (623 m) above sea level, the 103rd floor observation deck (The Sky deck) is 1,353 feet (412 m) above street level or 1,948 feet (593 m) above sea level, the Wacker Drive main entrance is 595 feet (181 m) above sea level. (The highest natural point in Illinois is the Charles Mound, at 1,235 feet (376 m) above sea level.)
• The building leans about 4 inches (10 cm) towards the west due to its slightly asymmetrical design, placing unequal loads on its foundation.
• The design for Willis Tower incorporates nine steel-unit square tubes in a 3 tube by 3 tube arrangement, with each tube having the footprint of 75 × 75 feet (22 × 22 m). Willis Tower was the first building for which this design was used. The design allows future growth of extra height to the tower if wanted or needed.^[44]
• The restrooms on the 103rd floor 1,353 feet (412 meters) above street level are the highest (relative to street level) in the Western Hemisphere.^[45]

Broadcasting

Many broadcast station transmitters are located at the top of Willis Tower. Each list is ranked by height from the top down. Stations at the same height on the same mast indicate the use of a diplexer into the same shared antenna. Due to its extreme height, FM stations (all class B) are very limited in power output.

Radio stations

East mast 482 m: WLIT FM 93.9 MHz main, 4.0 kW, AMFM WNUA FM 95.5 backup, 3.1 kW, AMFM 480 m: WJMK FM 104.3 main, 4.1 kW, CBS Radio 476 m: WTMX FM 101.9 main, 4.2 kW, Bonneville 474 m: WBBM FM 96.3 main, 4.2 kW, CBS Radio 472 m: WKSC FM 103.5 main, 4.3 kW, AMFM WGCI FM 107.5 main, 3.7 kW, AMFM 470 m: WFMT FM 98.7, 6.0 kW 468 m: WLS FM 94.7 main, 4.4 kW FCC query

West mast 460 & 451 m: WFMT FM 98.7 backups 443 m: WBBM-FM 96.3 backup WJMK FM 104.3 backup unknown: W264BF 100.7 MHz, 2 W, Calvary Chapel of Costa Mesa table of allotments: **WLIT, WLS, WBBM, WTMX, WJMK, WCFS FCC query

Also WB(Weather band)/WX (aka NOAA Weather Radio) transmit off the top of the Willis Tower on frequency 162.550 MHz (Channel 7) known as KWO39. Also equipped with SAME (Specific Area Message Encoding) for text alerts and hazardous weather alarm on weather radios. For weather radio station listing, please visit http://www.nws.noaa.gov/nwr/ for more information.

Television stations

East mast 515 m: WLS-TV 7 analog, 55 kW, Disney-ABC (Analog Broadcast discontinued as of June 12, 2009. Now broadcasting only in digital.) WLS-TV 7 permanent digital, 4.75 kW 510 m: WCPX TV 43 digital, 200 kW, Paxson WCPX TV 38 analog, 3630 kW, Paxson (Analog Broadcast discontinued as of June 12, 2009. Now broadcasting only in digital.) WJYS TV 36 digital, 145 kW, Jovon Broadcasting WCIU-TV 27 digital, 15.1 kW, Weigel Broadcasting 509 m: WXFT-TV 59 temporary digital, 200 kW, Telefutura, Univision Communications WXFT-TV 50 permanent digital, 230 kW, TeleFutura 498 m: WTTW TV 11 analog, 60.3 kW, Window To the World Comm. (Analog Broadcast discontinued as of June 12, 2009. Now broadcasting only in digital.) WBBM-TV 12 digital, 8 kW, CBS 480 m: WFLD TV 31 digital backup, 475 kW, Fox TV WPWR-TV 51 digital backup, 508 kW, Fox TV 478 m: WGN-TV 19 digital backup, 310/229 kW, Continental Broadcasting 474 m: WTTW TV 47 digital backup, 150 kW, Window To the World Comm. WLS-TV 52 digital backup, 220 kW, WLS TV unknown: W40BY 40 analog, 37.2 kW, Trinity Broadcasting Network FCC query

West mast 523 m: WPWR-TV 51 digital, 1000 kW, Fox TV 514 m, WLS-TV 52 temporary digital, 153.6 kW, WLS 508 m, WMAQ-TV 29 digital, 350 kW, NBC/Telemundo 494 m: WMAQ-TV 5 analog, 20 kW (Analog Broadcast discontinued as of June 12, 2009. Now broadcasting only in digital.) WPWR-TV 50 analog, 5000 kW (Analog Broadcast discontinued as of June 12, 2009. Now broadcasting only in digital.) WXFT-TV 60 analog, 5000 kW, TeleFutura (Analog Broadcast discontinued as of June 12, 2009. Now broadcasting only in digital.) 475 m: WFLD TV 31 digital, 690/1000 kW, Fox TV 473 m: WCIU-TV 26 analog, 5000 kW (Analog Broadcast discontinued as of June 12, 2009. Now broadcasting only in digital.) 472 m: WCIU-TV 27 digital, 590 kW, WCIU-TV WSNS-TV 44 analog 5000 kW, NBC Telemundo (Analog Broadcast discontinued as of June 12, 2009. Now broadcasting only in digital.) WSNS-TV 45 digital 467/665 kW, NBC Telemundo 465 m: WTTW TV 47 digital, 300 kW, Window To the World Comm. 455 m: WJYS TV 36 digital, 50 kW, Jovon Broadcasting 453 m: WGN-TV 19 digital, 645 kW, Continental Broadcasting unknown: WWME-LD 39 digital, 4.4 kW, Ch. 23 Ltd. WEDE-CA 34 analog, 50 kW, First United WMEU-CA 48 analog STA, 150 kW, Weigel Broadcasting WMEU-LD 32 digital, 15 kW FCC query

Gallery

Click on the images to see them larger

Willis Tower as seen from John Hancock Center observation deck	900 North Michigan, Park Tower, the John Hancock Center, the Trump Tower, and Aon Center (L-R) as seen from the Willis Tower Skydeck.	Westward view from Willis Tower	Panorama of Chicago skyline as seen from the Willis Tower Skydeck
View down to South Wacker Drive from the Skydeck

See also

	Chicago portal
	Illinois portal
	Architecture portal

Wikimedia Commons has media related to: Willis Tower

• Sears Merchandise Building Tower - original Sears Tower
• Sears, Roebuck and Company Administration Building
• Chicago architecture
• List of tallest buildings by U.S. state
• List of tallest buildings in the United States
• List of tallest buildings in Chicago
• List of towers
• World's tallest structures
• List of tallest freestanding structures in the world
• List of buildings with 100 floors or more
• WLS-TV

References

1. ^ ^{a b c} 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 Retrieved on June 7, 2008
2. ^ "Welcome to Sears Tower (Chicago, Illinois)". Searstower.org. Retrieved 2009-09-14.
3. ^ "Sears Tower Being Renamed", Chicago Breaking News, Mar 2009
4. ^ Kerch, Steve (October 20, 1991). "This job is a tall order Sears Tower project is the height of redevelopment." Chicago Tribune.
5. ^ "The Tallest Skyscraper", TIME, 11 Jun 1973
6. ^ "Databank: Sears Tower", Wonders of the World, PBS Databank. Retrieved November 19, 2007.
7. ^ SkyscraperPage - Sears Tower. Federal Communications Commission, CTBUH
8. ^ For information on this transformation, see Donald R. Katz The Big Store: Inside the Crisis and Revolution at Sears, New York (Viking), 1987.
9. ^ "77 W. Wacker ready to go." Chicago Sun-Times. March 12, 1990. Retrieved on November 12, 2009.
10. ^ Cliff Edwards, Associated Press. "TrizecHahn buys control of Chicago's Sears Tower World's 2d-tallest building sold for $110m", The Boston Globe, 4 Dec 1997. Retrieved 25 Feb 2009 from HighBeam Research
11. ^ "Sears Tower may be for sale", Crains Chicago Business, 31 Oct 1997
12. ^ "Trizec to sell its last local asset", Crain's Chicago Business, 27 Sep 2006
13. ^ "BIZ BRIEFS", Chicago Sun-Times, 1 May 2004. Retrieved 25 Feb 2009 from HighBeam Research
14. ^ "MetLife to Complete Sale of Chicago's Sears Tower", Chicago Tribune (Chicago, IL), 30 Apr 2004. Retrieved 25 Feb 2009 from HighBeam Research
15. ^ "FBI Killed Plot in Talking Stage". New York Times, June 24, 2006.
16. ^ "Seven charged over 'Chicago plot'". BBC News, June 23, 2006.
17. ^ "Sears Tower 'plot trial' begins", BBC News, October 3, 2007.
18. ^ "Five guilty in Chicago bomb plot", BBC News, May 12, 2009.
19. ^ "Sears Tower bomb plot leader Narseal Batiste jailed", BBC News, 20 Nov 2009.
20. ^ "Sears Tower in silver?", Chicago Sun-Times, 25 Feb 2009
21. ^ David Roeder. "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, 12 Oct 2007. Retrieved 25 Feb 2009 from HighBeam Research
22. ^ "Sears Tower unveils 103rd floor glass balconies", USA Today, 1 Jul 2009
23. ^ "The Ledge at Skydeck Chicago". SOM.com Project Page
24. ^ "'Spiderman' scales Sears Tower in Chicago - August 20, 1999". CNN. Retrieved 2009-09-14.
25. ^ Burj Khalifa surpasses the height of Sears Tower in Chicago^{[dead link]}
26. ^ "Freedom Tower ("World Trade Center 1")". NYC Tower. Retrieved 2008-11-30.
27. ^ Chicago Spire, Chicago - SkyscraperPage.com
28. ^ "Sears Tower name to change to Willis Tower". Chicago Tribune. March 12, 2009. Retrieved May 1, 2009.
29. ^ "Sears Tower Now Willis". Chicago Tribune. July 16, 2009. Retrieved July 16, 2009.
30. ^ Willis could get Sears Tower naming rights - Chicago Real Estate Daily - March 11, 2009
31. ^ ^{a b} Podmolik, Mary Ellen (July 16, 2009). "Sears Tower name change: Building today officially becomes Willis Tower". Chicago Tribune. Retrieved July 16, 2009.
32. ^ Burns, Greg (July 16, 2009). "Burns on Business, Willis Wants to be Part of Chicago by Way of Jersey". Chicago Tribune. Retrieved July 16, 2009.
33. ^ Podmolik, Mary Ellen (2009). "Sears Tower name change has few Chicago fans - Willis Tower may have trouble winning over public". Chicago Tribune (The Tribune Company) (March 13, 2009).
34. ^ "Sears Tower Now Named Willis Tower". CNN. July 16, 2009. Retrieved July 17, 2009.
35. ^ Johnson, Geoffrey (2010). "Top 40 Buildings in Chicago". Chicago (The Tribune Company) (October 2010).
36. ^ Suddath, Claire (February 8, 2010). "Top 10 Worst Corporate Name Changes: It's the Sears Tower". Time. Retrieved February 8, 2010.
37. ^ "Filming Locations for Ferris Bueller's Day Off". Movie-locations.com. Retrieved 2009-09-14.
38. ^ The Sears Tower Dressed In Sears Clothing
39. ^ By Keith Darcé (2007-01-31). "Madison Avenue turns to Main Street | The San Diego Union-Tribune". Signonsandiego.com. Retrieved 2009-09-14.
40. ^ SkyscraperDefense.com
41. ^ "SKYSCRAPERMAN". skyscraperman.com. Retrieved 2009-09-15.
42. ^ Sears Tower in Chicago Is Scaled by Stunt Man Published: May 26, 1981 New York Times
43. ^ "Spiderman scales Sears Tower w/Stan Lee interview". YouTube.com. Retrieved 2009-01-13.
44. ^ "Sears Tower". Tallest Building in the World. 2007-09-02. Retrieved 2009-09-14.
45. ^ Why Was the Sears Tower Built?, additional text.

External links

• Official Willis Tower office-space leasing website
• Willis Tower on Emporis
• Willis Tower Skydeck website
• Willis Tower at Structurae

Records
Preceded by World Trade Center	Tallest building in the world 1,451 ft 1974–1998	Succeeded by Petronas Twin Towers
	World's tallest building architectural element 442 m 1973–1998
	Building with the most floors 108 floors 2001–2007	Succeeded by Burj Khalifa
	World's tallest building rooftop 442 m 1973–2003	Succeeded by Taipei 101
	Tallest building in the United States 527 m 1973–present	Incumbent
Preceded by Aon Center	Tallest building in Chicago 527 m 1973–present

[show]v · d · eCity of Chicago

[show]v · d · eSupertall skyscrapers

[show]v · d · eChicago Skyscrapers

Categories: 1973 architecture | Buildings and structures on U.S. Route 66 | Visitor attractions along U.S. Route 66 | Former world's tallest buildings | Landmarks in Chicago, Illinois | Skyscrapers in Chicago, Illinois | Skyscrapers over 350 meters | Retail company headquarters in the United States | Office buildings in Chicago, Illinois | Skidmore, Owings and Merrill buildings | Visitor attractions in Chicago | United Airlines