John Hancock Observatory
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875 North Michigan Avenue (officially known until 2018 as the John Hancock Center and still commonly referred to under that name) is a 100-
story Story or stories may refer to: Common uses * Narrative, an account of imaginary or real people and events ** Short story, a piece of prose fiction that typically can be read in one sitting ** News story, an event or topic reported by a news orga ...
, supertall
skyscraper A skyscraper is a tall continuously habitable building having multiple floors. Most modern sources define skyscrapers as being at least or in height, though there is no universally accepted definition, other than being very tall high-rise bui ...
located in
Chicago Chicago is the List of municipalities in Illinois, most populous city in the U.S. state of Illinois and in the Midwestern United States. With a population of 2,746,388, as of the 2020 United States census, 2020 census, it is the List of Unite ...
, Illinois. Located in the
Magnificent Mile The Magnificent Mile (sometimes locally abbreviated to the Mag Mile) is the approximately one-mile-long stretch of Michigan Avenue (Chicago), Michigan Avenue from the Chicago River to Oak Street (Chicago), Oak Street on the Near North Side ...
district, the building was designed by Peruvian-American chief designer
Bruce Graham Bruce John Graham (December 1, 1925 – March 6, 2010) was a Colombian-born Peruvian-American architect. Graham built buildings all over the world and was deeply involved with evolving the Burnham Plan of Chicago. Among his most notable buil ...
and Bangladeshi-American structural engineer
Fazlur Rahman Khan Fazlur Rahman Khan (, ''Fazlur Rôhman Khan''; 3 April 1929 – 27 March 1982) was a Bangladeshi-American structural engineer and architect, who initiated important structural systems for skyscrapers. Considered the "father of Tube (structure) ...
of
Skidmore, Owings and Merrill SOM, an initialism of its original name Skidmore, Owings & Merrill LLP, is a Chicago-based architectural, urban planning, and engineering firm. It was founded in 1936 by Louis Skidmore and Nathaniel Owings. In 1939, they were joined by enginee ...
(SOM). When the building topped out on May 6, 1968, it was the second-tallest building in the world after the
Empire State Building The Empire State Building is a 102-story, Art Deco-style supertall skyscraper in the Midtown South neighborhood of Manhattan, New York City, United States. The building was designed by Shreve, Lamb & Harmon and built from 1930 to 1931. Its n ...
, in New York City, and the tallest in Chicago. It is currently the fifth-tallest building in Chicago and the fourteenth-tallest in the United States, behind the Aon Center in Chicago and ahead of the
Comcast Technology Center The Comcast Technology Center is a supertall skyscraper in Center City Philadelphia. The 60-floor building, with a height of , is the tallest building in both Philadelphia and the state of Pennsylvania and the tallest building in the Wester ...
in
Philadelphia Philadelphia ( ), colloquially referred to as Philly, is the List of municipalities in Pennsylvania, most populous city in the U.S. state of Pennsylvania and the List of United States cities by population, sixth-most populous city in the Unit ...
. When measured to the top of its antenna masts, it stands at . The building is home to several offices and restaurants, as well as about 700
condominium A condominium (or condo for short) is an ownership regime in which a building (or group of buildings) is divided into multiple units that are either each separately owned, or owned in common with exclusive rights of occupation by individual own ...
s; at the time of its completion, it contained the highest residence in the world. The building was originally named for John Hancock Mutual Life Insurance Company, a developer and original tenant of the building, which itself was named for the U.S.
Founding Father The following is a list of national founders of sovereign states who were credited with establishing a state. National founders are typically those who played an influential role in setting up the systems of governance, (i.e., political system ...
John Hancock John Hancock ( – October 8, 1793) was an American Founding Fathers of the United States, Founding Father, merchant, statesman, and prominent Patriot (American Revolution), Patriot of the American Revolution. He was the longest-serving Presi ...
. In 2018, John Hancock Insurance, years after leaving the building, requested that its name be removed; the owner is seeking another naming rights deal."John Hancock Center skyscraper losing its iconic name"
. ''Chicago Tribune'', February 12, 2018.
From the 95th-floor restaurant, which closed in late 2023, diners were able to look out at Chicago and
Lake Michigan Lake Michigan ( ) is one of the five Great Lakes of North America. It is the second-largest of the Great Lakes by volume () and depth () after Lake Superior and the third-largest by surface area (), after Lake Superior and Lake Huron. To the ...
. The observatory (360 Chicago), which competes with the Willis Tower's Skydeck, has a 360° view of the city, up to four states, and a distance of over . 360 Chicago is home to TILT, a moving platform that leans visitors over the edge of the skyscraper to a 30-degree angle, a full bar with local selections, Chicago's only open-air SkyWalk, and also features free interactive high-definition touchscreens in six languages. The 44th-floor
sky lobby A sky lobby is an intermediate interchange floor in a skyscraper where people can change from an express elevator that stops only at the sky lobby to a local elevator that stops at a subset of higher floors. Early uses of the sky lobby include ...
features the highest indoor swimming pool in the
United States The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...
.


History


20th century

The project, which would become the world's second tallest building at opening, was conceived and owned by
Jerry Wolman Jerry Wolman (February 14, 1927 – August 6, 2013) was an American developer in Washington, D.C. and owned the Philadelphia Eagles of the National Football League in the 1960s. Early years Wolman was born to an Orthodox Jewish family in Sh ...
in late 1964. The project was financed by John Hancock Mutual Life Insurance Company. Construction of the tower was interrupted in 1967 due to a flaw in an innovative engineering method used to pour concrete in stages, that was discovered when the building was 20 stories high. The engineers were getting the same soil settlements for the 20 stories that had been built as what they had expected for the ''entire'' 99 stories. This forced the owner to stop development until the engineering problem could be resolved, resulting in a credit crunch. The situation is similar to the one faced during the construction of 111 West Wacker, then known as the
Waterview Tower OneEleven (formerly 111 W. Wacker and Waterview Tower) is a luxury rental apartment tower located in downtown Chicago, Illinois. The building is located between LaSalle Street and Clark Street, adjacent to River North and directly on the Chicag ...
. Wolman's bankruptcy resulted in John Hancock taking over the project, which retained the original design, architect, engineer, and main contractor. The building's first resident was Ray Heckla, the original building engineer, responsible for the residential floors from 44 to 92. Heckla moved his family in April 1969, before the building was completed. The 1988 film ''
Poltergeist III ''Poltergeist III'' is a 1988 American supernatural horror film co-written and directed by Gary Sherman, and starring Tom Skerritt, Nancy Allen, Heather O'Rourke and Zelda Rubinstein with the latter two reprising their roles from the previou ...
'' was set at the John Hancock Center and was filmed in early 1987.


21st century

On December 10, 2006, the non-residential portion of the building was sold by
San Francisco San Francisco, officially the City and County of San Francisco, is a commercial, Financial District, San Francisco, financial, and Culture of San Francisco, cultural center of Northern California. With a population of 827,526 residents as of ...
–based
Shorenstein Properties Shorenstein is a real estate investment company based in San Francisco that owns interests in of office space throughout the United States. The company has sponsored twelve closed-end real estate funds, with total equity commitments of $8.8 bill ...
for $385 million and was purchased by a joint venture of Chicago-based Golub & Company and the Whitehall Street Real Estate Funds.
Shorenstein Properties Shorenstein is a real estate investment company based in San Francisco that owns interests in of office space throughout the United States. The company has sponsored twelve closed-end real estate funds, with total equity commitments of $8.8 bill ...
had bought the building in 1998 for $220 million. Golub defaulted on its debt and the building was acquired in 2012 by
Deutsche Bank Deutsche Bank AG (, ) is a Germany, German multinational Investment banking, investment bank and financial services company headquartered in Frankfurt, Germany, and dual-listed on the Frankfurt Stock Exchange and the New York Stock Exchange. ...
, who subsequently carved up the building. The venture of Deutsche Bank and New York–based NorthStar Realty Finance paid an estimated $325 million for debt on 875 North Michigan Avenue in 2012 after
Shorenstein Properties Shorenstein is a real estate investment company based in San Francisco that owns interests in of office space throughout the United States. The company has sponsored twelve closed-end real estate funds, with total equity commitments of $8.8 bill ...
defaulted on $400 million in loans. The observation deck was sold to Paris-based Montparnasse 56 Group for between $35 million and $45 million in July 2012. That same month, Prudential Real Estate Investors acquired the retail and restaurant space for almost $142 million. In November 2012, Boston-based American Tower Corp affiliate paid $70 million for the antennas. In June 2013, a venture of Chicago-based real estate investment firm Hearn Co., New York–based investment firm Mount Kellett Capital Management L.P. and San Antonio–based developer Lynd Co. closed on the expected acquisition of 875 North Michigan Avenue's of office space and 710-car parking deck. The Chicago firm did not disclose a price, but sources said it was about $145 million.New owners of Hancock office space plan $45 million rehab
''chicagobusiness.com''
This was the last step in that piecemeal sale process. In May 2016, Hearn Co. announced that they were seeking buyers for the naming rights with possible signage rights for the building. Hustle up the Hancock is an annual stair climb race up the 94 floors from the Michigan Avenue level to the observation deck. It is held on the last Sunday of February. The climb benefits Respiratory Health Association. The record time as of 2007 is 9 minutes 30 seconds. The building is home to the transmitter of
Univision Univision () is an American Spanish-language terrestrial television, free-to-air television network owned by TelevisaUnivision. It is the United States' largest provider of Spanish-language content. The network's programming is aimed at the L ...
's
WGBO-DT WGBO-DT (channel 66) is a television station licensed to Joliet, Illinois, United States, serving as the Chicago-area outlet for the Spanish-language network Univision. It is owned and operated by TelevisaUnivision alongside Aurora-licensed Uni ...
(channel 66), while all other full-power television stations in Chicago broadcast from
Willis Tower The Willis Tower, formerly and still commonly referred to as the Sears Tower, is a 110-storey, story, skyscraper in the Chicago Loop, Loop community area of Chicago in Illinois, United States. Designed by architect Bruce Graham and engineer F ...
. The
City Colleges of Chicago The City Colleges of Chicago is the public community college system of the Chicago area. Its colleges offer associate degrees, certificates, free courses for the GED, and free English as a second language (ESL) courses. The City Colleges sys ...
's
WYCC WYCC (channel 20) was a public television station in Chicago, Illinois, United States. It was last owned by not-for-profit broadcasting entity Window to the World Communications, Inc., alongside PBS member station WTTW (channel 11) and classi ...
(channel 20) transmitted from the building until November 2017, when it departed the air as part of the 2016 FCC spectrum auction. On February 12, 2018, John Hancock Insurance requested that its name and logos throughout the building's interior be removed immediately; John Hancock had not had a naming-rights deal with the skyscraper's owners since 2013. The building's name was subsequently changed to its street address as 875 North Michigan Avenue. The Signature Room restaurant on the 95th and 96th floors was listed for sale in April 2023 and closed that September, with ownership citing "severe economic hardship" that they attributed to the impact of the earlier
COVID-19 pandemic The COVID-19 pandemic (also known as the coronavirus pandemic and COVID pandemic), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), began with an disease outbreak, outbreak of COVID-19 in Wuhan, China, in December ...
. 360 CHICAGO, which operated the 94th-floor observation deck, bought the building's 95th and 96th floors in June 2024. The next year, it was announced that 875 North Michigan's observation deck would be expanded into the former Signature Room space. Skidmore, Owings & Merrill (the architectural firm that designed the building in the 1970s) was hired to redesign these two floors.


Incidents

On November 11, 1981,
Veterans Day Veterans Day (originally known as Armistice Day) is a federal holiday in the United States observed annually on November 11, for honoring military veterans of the United States Armed Forces. It coincides with holidays in several countries, i ...
, high-rise firefighting and rescue advocate
Dan Goodwin Daniel Goodwin (born November 7, 1955, in Kennebunkport, Maine) is an American climber best known for performing gymnastic-like flag maneuvers and one-arm flyoffs while free soloing difficult rock climbs on national TV and for scaling towering ...
, for the purpose of calling attention to the inability to rescue people trapped in the upper floors of skyscrapers, successfully climbed the building's exterior wall. Wearing a wetsuit and using a climbing device that enabled him to ascend the I-beams on the building's side, Goodwin battled repeated attempts by the
Chicago Fire Department The Chicago Fire Department (CFD) provides firefighting services along with emergency medical response services, hazardous materials mitigation services, and technical rescue response services in the city of Chicago, Illinois, United States, un ...
to knock him off. Fire Commissioner William Blair ordered Chicago firemen to stop Goodwin by directing a fully engaged fire hose at him and by blasting fire axes through nearby glass from the inside. Fearing for Goodwin's life, Mayor
Jane Byrne Jane Margaret Byrne (née Burke; May 24, 1933November 14, 2014) was an American politician who served as the 50th mayor of Chicago from April 16, 1979, until April 29, 1983. Prior to her tenure as mayor, Byrne served as Chicago's commissioner of ...
intervened and allowed him to continue to the top. On December 18, 1997, comedian
Chris Farley Christopher Crosby Farley (February 15, 1964 – December 18, 1997) was an American actor and comedian. He was a member of Chicago's Second City Theatre and later a cast member of the NBC sketch comedy show ''Saturday Night Live'' for fiv ...
was found dead in his apartment on the 60th floor of the building. On March 9, 2002, part of a scaffold fell 43 stories after being torn loose by wind gusts around crushing several cars, killing three people in two of them. The remaining part of the stage swung back-and-forth in the gusts repeatedly slamming against the building, damaging cladding panels, breaking windows, and sending pieces onto the street below. On November 21, 2015, a fire broke out in an apartment on the 50th floor of the building. The
Chicago Fire Department The Chicago Fire Department (CFD) provides firefighting services along with emergency medical response services, hazardous materials mitigation services, and technical rescue response services in the city of Chicago, Illinois, United States, un ...
was able to extinguish the fire after an hour and a half; five people suffered minor injuries. On February 11, 2018, a fire in a car on the seventh floor required approximately 150 firefighters to extinguish. On November 16, 2018, an express elevator cable broke. Initial reports stated that an elevator with six passengers plunged 84 stories from the 95th to 11th floor. Since express elevators are not accessible from floors within the express zone, a team of firefighters had to break through a brick wall from the parking garage to extricate the passengers, none of whom suffered injuries. Elevators to the 95th/96th floor were closed thereafter pending investigation. Subsequent investigation documented only a controlled descent from the 20th floor to the 11th floor. On January 5, 2022, a piece of cladding fell from the building.


Architecture

One of the most famous buildings of the
structural expressionist High-tech architecture, also known as structural expressionism, is a type of late modernist architecture that emerged in the 1970s, incorporating elements of high tech industry and technology into building design. High-tech architecture grew fro ...
style, the skyscraper's distinctive X-braced exterior shows that the structure's skin is part of its " tubular system". This is one of the engineering techniques which the designers used to achieve a record height; the tubular system is the structure that keeps the building upright during wind and earthquake loads. This X-bracing allows for both higher performance from tall structures and the ability to open up the inside floorplan. Such original features have allowed 875 North Michigan Avenue to become an architectural icon. It was pioneered by Bangladeshi-American structural civil engineer
Fazlur Khan Fazal ur Rahman or variants may refer to the following people: Politicians *Fazal-ur-Rehman (politician) (born 1953), Pakistani Islamic fundamentalist politician *Fazlur Rehman Khalil (born 1963), Pakistani Islamist politician *Fazlur Rahman Mal ...
and chief architect
Bruce Graham Bruce John Graham (December 1, 1925 – March 6, 2010) was a Colombian-born Peruvian-American architect. Graham built buildings all over the world and was deeply involved with evolving the Burnham Plan of Chicago. Among his most notable buil ...
. The interior was remodeled in 1995, adding to the lobby
travertine Travertine ( ) is a form of terrestrial limestone deposited around mineral springs, especially hot springs. It often has a fibrous or concentric appearance and exists in white, tan, cream-colored, and rusty varieties. It is formed by a process ...
, black granite, and textured
limestone Limestone is a type of carbonate rock, carbonate sedimentary rock which is the main source of the material Lime (material), lime. It is composed mostly of the minerals calcite and aragonite, which are different Polymorphism (materials science) ...
surfaces. The elliptical-shaped plaza outside the building serves as a public oasis with seasonal plantings and a 12-foot (3.7 m) waterfall. A band of white lights at the top of the building is visible all over Chicago at night, and changes colors for different events. For example, at Christmas time the colors are green and red. When a Chicago-area sports team goes far in the playoffs, the colors are changed to match that team's colors. The building is a member of the World Federation of Great Towers. It has won various awards for its distinctive style, including the Distinguished Architects
Twenty-five Year Award The Twenty-five Year Award is an architecture prize awarded each year by the American Institute of Architects (AIA) to "a building that has set a precedent for the last 25 to 35 years and continues to set standards of excellence for its architec ...
from the
American Institute of Architects The American Institute of Architects (AIA) is a professional organization for architects in the United States. It is headquartered in Washington, D.C. AIA offers education, government advocacy, community redevelopment, and public outreach progr ...
in May 1999. In celebration of the 2018 Illinois Bicentennial, the John Hancock Center was selected as one of the Illinois 200 Great Places by the
American Institute of Architects The American Institute of Architects (AIA) is a professional organization for architects in the United States. It is headquartered in Washington, D.C. AIA offers education, government advocacy, community redevelopment, and public outreach progr ...
Illinois component (AIA Illinois) and was recognized by USA Today Travel magazine, as one of AIA Illinois' selections for Illinois 25 Must See Places. The building is only partially protected by a fire sprinkler system, as the residential floors do not have sprinklers. Including its antennas, the building has a height of , making it the thirty-third tallest building in the world when measured to pinnacle height.


Interior spaces


44th floor sky lobby

The 44th level
skylobby A sky lobby is an intermediate interchange floor in a skyscraper where people can change from an express elevator that stops only at the sky lobby to a local elevator that stops at a subset of higher floors. Early uses of the sky lobby include ...
is the floor where the building transitions from offices to residential, with offices occupying floors below and residences occupying floors above.


Swimming pool

On its 44th floor, the John Hancock Center has a resident
swimming pool A swimming pool, swimming bath, wading pool, paddling pool, or simply pool, is a structure designed to hold water to enable Human swimming, swimming and associated activities. Pools can be built into the ground (in-ground pools) or built abo ...
. The pool area has double-height ceilings. The pool is the highest pool in the United States when measured by distance above ground level.


Resident/office tenant grocery store

On its 44th floor, the building has a
grocery store A grocery store ( AE), grocery shop or grocer's shop ( BE) or simply grocery is a retail store that primarily retails a general range of food products, which may be fresh or packaged. In everyday US usage, however, "grocery store" is a synon ...
accessible only to apartment residents and office tenants. In 2007, operation of the grocery store was taken over by the local Potash chain of grocery stores. As of February 2023, Potash continues to operate the grocery store.


Upper floors


Express elevators

The elevators that serve the top three public floors are credited as the fastest in both North America and the Western Hemisphere. Manufactured by Otis, the elevators travel 96 floors at a top speed of . It has been said that they would be capable of reaching the 95th floor in 38 seconds if they could run the entire trip at their top speed.


360 Chicago Observation Deck

Located on the 94th floor, 360 Chicago Observation Deck is 875 North Michigan Avenue's horizon observatory. The floor of the observatory is above the street-level below. The entrance can be found on the concourse level of 875 North Michigan Avenue, accessible from the Michigan Avenue side of the building. The observatorywas previously named "John Hancock Observatory". It has been independently owned and operated since 2014 as an subsidiary of the
Paris Paris () is the Capital city, capital and List of communes in France with over 20,000 inhabitants, largest city of France. With an estimated population of 2,048,472 residents in January 2025 in an area of more than , Paris is the List of ci ...
,
France France, officially the French Republic, is a country located primarily in Western Europe. Overseas France, Its overseas regions and territories include French Guiana in South America, Saint Pierre and Miquelon in the Atlantic Ocean#North Atlan ...
-based observation deck company Magnicity (formerly known as the "Montparnasse 56 Group"). After its acquisition of the observation deck, the company extensively renovated the space in 2014. The observatory boasts more floor space than its direct competitor, Skydeck at the Willis Tower. The observation deck currently includes a cocktail lounge named the "CloudBar". After the closure of the building's 96th floor cocktail lounge, 360 CHICAGO has advertised it as being the highest cocktail lounge in the city. It was formerly named "BAR 94". In the summer of 2014, 360 Chicago added its TILT attraction. TILT, which requires an additional fee to experience, features a series of floor-to-ceiling windows that slowly tilt outside the building to 30°. The observation deck also features an open-air "skydeck" area. For several years in the 2010s, during its winter season, the observation deck would feature the "world's highest skating rink", with an
artificial ice rink An ice rink (or ice skating rink) is a frozen body of water or an artificial sheet of ice where people can ice skate or play winter sports. Ice rinks are also used for exhibitions, contests and ice shows. The growth and increasing popularity of ...
being seasonally installed. At one point, observation deck had a
mascot A mascot is any human, animal, or object thought to bring luck, or anything used to represent a group with a common public identity, such as a school, sports team, university society, society, military unit, or brand, brand name. Mascots are als ...
named Seemore Miles.


Former 95th floor restaurant and 96th floor cocktail lounge

Separate from its observatory, 875 Michigan Avenue formerly had a restaurant space on its 95th floor and a cocktail lounge space on its 96th floor. The combined space on these floors was approximately . The original restaurant in this space was named "The 95th restaurant", which operated from the 1970s until 1993. Its accompanying 96th floor cocktail lounge was named "Images". From 1993 until 2023, the 95th floor was home to a restaurant named the "Signature Room", with the accompanying cocktail lounge on the 96th floor being named the "Signature Lounge". The name alluded to the famous
signature A signature (; from , "to sign") is a depiction of someone's name, nickname, or even a simple "X" or other mark that a person writes on documents as a proof of identity and intent. Signatures are often, but not always, Handwriting, handwritt ...
of early American figure
John Hancock John Hancock ( – October 8, 1793) was an American Founding Fathers of the United States, Founding Father, merchant, statesman, and prominent Patriot (American Revolution), Patriot of the American Revolution. He was the longest-serving Presi ...
. The restaurant was an upscale establishment that offered patrons scenic views. It enforced a dress code for patrons. It received numerous awards. In September 2023, the Signature Room abruptly ceased operations.


Parking garage

Housed within several of the lower levels of the building is a
parking garage A multistorey car park (Commonwealth English) or parking garage (American English), also called a multistorey, parking building, parking structure, parkade (Canadian), parking ramp, parking deck, or indoor parking, is a building designed fo ...
, which cars enter and depart via a spiral vehicle ramp.


Other features


Retail plaza

The building features a two-level outdoor plaza along its Michigan Avenue face. The plaza contains retail and dining tenants. The top level of the plaza is at street level, while the lower level is sunken below the street level. Current tenants include
The Cheesecake Factory The Cheesecake Factory Incorporated is an American restaurant company and distributor of cheesecakes based in the United States. It operates 348 full-service restaurants: 215 under the Cheesecake Factory brand, 42 under the North Italia brand, a ...
and
The North Face The North Face is an American outdoor recreation products company. The North Face produces outdoor clothing, footwear, and related equipment. Founded in 1968 to supply climbers, the company's logo draws inspiration from Half Dome, a distinct ...
. Past tenants have included
Best Buy Best Buy Co., Inc. is an American multinational consumer electronics retailer headquartered in Richfield, Minnesota. Originally founded by Richard M. Schulze and James Wheeler in 1966 as an audio specialty store called Sound of Music, it was r ...
. The plaza was originally rectangular in shape. Per the ''
Chicago Tribune The ''Chicago Tribune'' is an American daily newspaper based in Chicago, Illinois, United States. Founded in 1847, it was formerly self-styled as the "World's Greatest Newspaper", a slogan from which its once integrated WGN (AM), WGN radio and ...
'', the plaza was modeled after the plaza at New York City's
Rockefeller Center Rockefeller Center is a complex of 19 commerce, commercial buildings covering between 48th Street (Manhattan), 48th Street and 51st Street (Manhattan), 51st Street in the Midtown Manhattan neighborhood of New York City. The 14 original Art De ...
. The plaza's design featured a fountain pool that would be turned into an ice rink in colder weather. In 1988, plans were unveiled by the John Hancock Mutual Life Insurance Company (the owners of the building at the time) to replace the plaza with a "$20 million glass and marble three-story atrium". One rationale cited by building's management was they claimed that access to the building's ground level was complicated by the need of pedestrians to circumnavigate around the courtyard in order to reach the street-level entrance to the building's lobby. They also cited a belief that the building's entrance was too understated for a building of its level of prominence. This atrium proposal faced backlash from local residents who felt that such an addition would mar the appearance of the landmark building. In 1989, newly-elected mayor
Richard M. Daley Richard Michael Daley (born April 24, 1942) is an American politician who served as the 54th mayor of Chicago, Illinois, from 1989 to 2011. Daley was elected mayor in 1989 and was reelected five times until declining to run for a seventh ter ...
criticized the proposed atrium and the plans were ultimately abandoned. In 1994, the plaza was renovated, with the sunken portion transforming from its previous rectangular shape to an elliptical shape. In 1999, ''Chicago Tribune'' architecture critic
Blair Kamin Blair Kamin was the architecture critic of the ''Chicago Tribune'', for 28 years from 1992 to 2021. Kamin has held other jobs at the Tribune and previously worked for ''The Des Moines Register''. He also serves as a contributing editor of ''Archit ...
wrote that this renovation had made the plaza a more "welcoming" space. This renovation came after the more dramatic late-1980s renovation plans were abandoned. A further $10 million renovation for the plaza was considered by the building's owners in the mid-2010s which would have added features such as video screens and decorative prisms to the plaza.


Antennas

Since its completion, the tower has been topped by two antenna structures. These antenna superstructures support a large number of broadcast antenna equipment. At the time of the tower's completion, both antenna structures were in height, and
RCA RCA Corporation was a major American electronics company, which was founded in 1919 as the Radio Corporation of America. It was initially a patent pool, patent trust owned by General Electric (GE), Westinghouse Electric Corporation, Westinghou ...
had given the architects of the building an estimate that 700 feet of antenna structure would be required to accommodate all of the city's radio and television stations. In 2002, the eastern antenna tower was extended to a height of in order to enable
WBBM-TV WBBM-TV (channel 2) is a television station in Chicago, Illinois, United States, serving as the market's CBS network outlet. Owned and operated by the network's CBS News and Stations division, the station maintains studios on West Washington St ...
to add new digital antenna equipment at a height greater than the roof height of the Sears Tower (Willis Tower). Subsequently, the western antenna tower was reduced to a height of . For a long time, the antenna towers utilized
incandescent Thermal radiation is electromagnetic radiation emitted by the thermal motion of particles in matter. All matter with a temperature greater than absolute zero emits thermal radiation. The emission of energy arises from a combination of electro ...
red lights and a red and white paint scheme to provide a visibility to aviation in compliance with federal regulations. However, in order to forgo the expense and effort of annually reapplying striped paint to the antenna towers, the tower instead installed red
strobe light A strobe light or stroboscopic lamp, commonly called a strobe, is a device used to produce regular flashes of light. It is one of a number of devices that can be used as a stroboscope. The word originated from the Ancient Greek ('), meaning ...
s atop the tower and eliminated the striped paint scheme, as striped paint is not required if structures are topped by such lights. A sizable number of television and radio stations utilize the antenna towers. Many stations maintain broadcast equipment on both the John Hancock Center and the Willis Tower's antenna structures in order to have both a primary and backup broadcasting point. In November 2012, Boston-based American Tower Corp affiliate paid $70 million to acquire ownership of the antennas.


See also

*
Architecture of Chicago The buildings and architecture of Chicago reflect the city's history and multicultural heritage, featuring prominent buildings in a variety of styles. Most structures downtown were destroyed by the Great Chicago Fire in 1871 (an exception being t ...
*
List of buildings and structures This is a list of list of buildings and nonbuilding structures. By type * List of abbeys and priories * List of contemporary amphitheatres, List of amphitheatres (contemporary) * List of Roman amphitheatres, List of amphitheatres (Roman) ...
*
List of buildings with 100 floors or more This is a list of buildings with 100 floors or more above ground. Dubai and Chicago have three buildings with at least 100 floors. All of the buildings on this list are over 1,000 ft (305 meter) "supertalls" and are among the world's tallest build ...
*
List of tallest buildings in the world This is a list of the tallest buildings. Tall buildings, such as skyscrapers, are intended here as enclosed structures with continuously occupiable floors and a height of at least . Such definition excludes non-building structures, such as tow ...
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List of tallest buildings in Chicago Chicago, the List of United States cities by population, third-largest city in the United States, is home to 1,397 completed high-rises, 56 of which stand taller than . The tallest building in the city is the 110-Storey, story Willi ...
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List of tallest buildings in the United States The world's first skyscraper was built in Chicago in 1885. Since then, the United States has been home to some of the world's tallest skyscrapers. New York City, and especially the borough of Manhattan, has the tallest skyline in the country. E ...
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List of tallest buildings and structures in the world This is the History of the world's tallest structures. Overall Below is a list of the tallest structures supported by land. For most of the period from around 2650 BC to 1240 AD, the Egyptian pyramids (culminating in the Great Pyramid of Giz ...
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List of tallest freestanding structures in the world The tallest structure in the world is the Burj Khalifa skyscraper at . Listed are guyed masts (such as telecommunication masts), self-supporting towers (such as the CN Tower), skyscrapers (such as the Willis Tower), oil platforms, electricity ...
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List of tallest freestanding steel structures This is a list of tallest freestanding steel structures in the world past and present. To be a freestanding steel structure it must not be supported by guy wires, the list therefore does not include guyed masts and the main vertical and lateral str ...


Footnotes


References

The Cloudbase Chronicles, Life at the Top - An engineers Tale by Harry W. Budge IIIOutskirts Press 2010


External links

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360 Chicago
formerly Hancock Observatory
875 North Michigan Avenue
on
CTBUH The Council on Tall Buildings and Urban Habitat (CTBUH) is an international body in the field of tall buildings, including skyscrapers, and sustainable urban design. A non-profit organization based at the Monroe Building in Chicago, Illinois, U ...
Skyscraper Center * *
John Hancock CenterSociety of Architectural Historians SAH ARCHIPEDIA entry on John Hancock Center
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