Citigroup Center

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601 Lexington Avenue
Citigroup Center
Citigroup center.jpg
General information
Type Office
Location 153 East 53rd Street, Manhattan, New York, United States
Coordinates 40°45′31″N 73°58′13″W / 40.758533°N 73.970314°W / 40.758533; -73.970314Coordinates: 40°45′31″N 73°58′13″W / 40.758533°N 73.970314°W / 40.758533; -73.970314
Construction started 1974
Completed 1977
Opening 1977
Cost $195 million (USD)
(in adjusted inflation $758,904,448)
Owner Boston Properties
Architectural 915 ft (279 m)[1]
Technical details
Floor count 59[1]
Design and construction
Architect Hugh Stubbins / KlingStubbins, Emery Roth & Sons
Developer Boston Properties
Structural engineer Le Messurier Consultants, James Ruderman

The Citigroup Center (formerly Citicorp Center and now known as 601 Lexington Avenue) is one of the ten tallest skyscrapers in New York City, located at 53rd Street between Lexington Avenue and Third Avenue in midtown Manhattan. The 59-floor, 915-foot (279-m) building contains 1.3 million square feet (120,000 m²) of office space, and is one of the most distinctive and imposing in New York's skyline, thanks to a 45° angled top and a unique stilt-style base. It was designed by architect Hugh Stubbins and structural engineer William LeMessurier for Citibank, and was completed in 1977. The building is currently owned by Boston Properties, and in 2009, was renamed 601 Lexington Avenue.


The northwest corner of the site was originally occupied by St. Peter's Evangelical Lutheran Church which was founded in 1862. In 1905, the church moved to the location of 54th Street and Lexington Avenue.

Early engineering details[edit]

Night View of Citigroup Center from GE Building.

From the beginning, the Citigroup Center was an engineering challenge. When planning for the skyscraper began in the early 1970s, the northwest corner of the proposed building site was occupied by St. Peter's Lutheran Church. The church allowed Citicorp to demolish the old church and build the skyscraper under one condition: a new church would have to be built on the same corner, with no connection to the Citicorp building and no columns passing through it, because the church wanted to remain on the site of the new development, near one of the intersections. Architects wondered at the time if this demand was too much and would make the proposal unfeasible.

Structural engineer William LeMessurier set the 59-story tower on four massive 114foot, (35metre or 14 storey), high columns, positioned at the center of each side, rather than at the corners. This design allowed the northwest corner of the building to cantilever 72 feet (22 m) over the new church. To accomplish these goals LeMessurier designed a system of stacked load-bearing braces, in the form of inverted chevrons. Each chevron would redirect the massive loads to their center, then downward into the ground through the uniquely positioned columns.

Engineering crisis of 1978[edit]

Changes during construction led to a finished product that was structurally unsound. In June 1978, prompted by discussion between a civil engineering student at Princeton University, Diane Hartley,[2] and design engineer Joel Weinstein, LeMessurier recalculated the wind loads on the building. In the original design, the engineer calculated for wind loads that hit the building straight-on, but he did not calculate for quartering wind loads, which hit the building at a 45-degree angle. This oversight revealed that quartering wind loads resulted in a 40% increase in wind loads and a 160% increase in the load at all connection joints. This discovery was rather disturbing, since a couple of weeks prior to that, LeMessurier had discovered a structural flaw, which was introduced during construction.

Earlier in May, LeMessurier met for an inquiry on another job where he mentioned the use of welded joints in the Citicorp building, only to find a potentially fatal flaw in the building's construction: the original design's welded joints were changed to bolted joints during construction, which were too weak to withstand 70-mile-per-hour (113 km/h) quartering winds. While LeMessurier's original design and load calculations for the special, uniquely designed "chevron" load braces used to support the building were based on welded joints, a labor- and cost-saving change altered the joints to bolted construction after the building's plans were approved.

Base of the Citigroup Center
View from the street

The engineers did not recalculate what the construction change would do to the wind forces acting on two surfaces of the building's curtain wall at the same time; if hurricane-speed winds hit the building at a 45-degree angle, there was the potential for failure due to the bolts shearing. The wind speeds needed to topple the models of Citigroup Center in a wind-tunnel test were predicted to occur in New York City every 55 years. If the building's tuned mass damper went offline, the necessary wind speeds were predicted to occur every 16 years.

This knowledge, combined with LeMessurier's discovery that his firm had used New York City's truss safety factor of 1:1 instead of the column safety factor of 1:2, meant that the building was in critical danger. The discovery of the problem occurred in the month of June, the beginning of hurricane season. The problem had to be corrected quickly.

It is reported that LeMessurier agonized over how to deal with the problem. If he made it known publicly, he risked ruining his professional reputation. He approached the architect (Hugh Stubbins) first, then Citicorp and advised them of the need to take swift remedial action, ultimately convincing the company to hire a crew of welders to repair the fragile building without informing the public, a task made easier by the press strike at that time.

For the next three months, a construction crew welded two-inch-thick steel plates over each of the skyscraper's 200 bolted joints during the night, after each work day, almost unknown to the general public. Six weeks into the work, a major storm (Hurricane Ella) was off Cape Hatteras and heading for New York. With New York City hours away from emergency evacuation, the reinforcement was only half-finished. Ella eventually turned eastward and veered out to sea, buying enough time for workers to permanently correct the problem.

Because nothing happened as a result of the engineering gaffe, the crisis was kept hidden from the public for almost 20 years. It was publicized in a lengthy article in The New Yorker in 1995.[3] LeMessurier was criticized for insufficient oversight leading to bolted rather than welded joints, for not only not informing the endangered neighbors but actively misleading the public about the extent of the danger during the reinforcement process, and for keeping the engineering insights from his peers for two decades.[4] However, his act of alerting Citicorp to the problem inherent in his own design is now used as an example of ethical behavior in several engineering textbooks.

Ethics involved[edit]

Eugene Kremer FAIA article "(RE)EXAMINING THE CITICORP CASE: Ethical Paragon or Chimera" discusses the ethical issue of not telling people and not allowing the engineering profession to learn from their mistakes, as it took 17 years to reveal to the public the truth. Kremer, an Architect, discusses 6 key points:

  1. - Analysis of wind loads. Check all calculations and not rely just on building codes, these set minimum requirements and not the state of the art.
  2. - Design changes. In this case change from welded to bolted connections. Changes are considered in the overall design context and by everyone involved and not a spur of the moment decision.
  3. - Professional responsibility. To follow the codes of conduct for every chartered institution. LeMessurier, in Kremer (2002), did not consider the public safety first.
  4. - Public statements. In this case the public statements issued by LeMessurier and Citigroup set out to deliberately mislead the public.
  5. - Public safety. The public statement denied the public the right to ensure their own safety and to make their own critical decisions.
  6. - Advancement of professional knowledge. By not telling the everyone of the buildings weakness for almost 20 years the ethical and engineering learning that could have taken place during this time was not allowed.



Former Citicorp Chairman Walter B. Wriston was reportedly behind the decision to acquire several low- and mid-rise buildings in the area for the purpose of ridding midtown of "those massage parlors.”[6] In 1987, Citigroup sold two-thirds of its interest in the building, along with one-third of its interest in 399 Park Ave, to Dai-Ichi Mutual Life Insurance Company for $670 million (total cost of building adjusted for inflation: $365,584,843).[7]

In 2001, Citicorp sold its controlling stake in the building for $755 million (cost of building adjusted for inflation: $569,794,069) to Boston Properties. Citigroup relocated to 399 Park Ave, where the company is currently headquartered.[8][9]

Name and address change[edit]

In 2008, building owner Boston Properties began the process of renaming the tower "601 Lexington Avenue".[10] Renovation of the lobby resulted in relocation of the tower's entrance from 53rd Street to Lexington Avenue.[11] All signage for Citigroup was removed from the building and surrounding block. The name change became effective in 2009.[12][13] The company is also considering selling naming rights to the building.[14]

Notable features[edit]

Public lobby
  • The roof of Citigroup Center slopes at a 45-degree angle because it was originally intended to contain solar panels to provide energy. However, this idea was eventually dropped because the positioning of the angled roof meant that the solar panels would not face the sun directly.
  • To help stabilize the building, a tuned mass damper was placed in the mechanical space at its top. This substantial piece of stabilizing equipment weighs 400 tons (350 metric tons). The damper is designed to counteract swaying motions due to the effect of wind on the building and reduces the building's movement due to wind by as much as 50%.[15] Citigroup Center was not the first skyscraper in the United States to feature a tuned mass damper. That distinction belongs to the John Hancock Tower in Boston.
  • The building features double-deck elevators, which are separated to serve only odd or even floors.
  • The corporate headquarters of Citigroup, contrary to popular perception, are not located in the building, but across the street in 399 Park Avenue.
  • The building is visible in numerous television shows and movies (often as part of a wider panoramic shot of New York City), notably during the opening credits of the long-running NBC police procedural and legal drama Law & Order, and it can also be seen in the background of the opening titles of the 1980s sitcom Taxi.
  • In 2002, one of the columns was reinforced with blast resistant shields of steel and copper as well as steel bracing to protect the building due to the possibility of a terrorist attack.[16]
  • From 1987 to 2009, the bank presented an annual toy train exhibition in the lower lobby.[17]

In popular culture[edit]

A season one episode of the TV show NUMB3RS, "Structural Corruption", involves a fictional building with faults almost exactly paralleling the crisis of the Citigroup Center. Like the Citigroup Center, a college student studying the fictional Cole Center finds the building to have inadequate strength when subjected to quartering winds. However, the insufficient welds in the Cole Center lie in the foundation, and a tuned mass-damper (not present in the original construction) is added to make the building safe.


In the TV show Suits, 601 Lexington is the address of the fictional law firm Pearson Hardman.

See also[edit]

Notes and references[edit]


  1. ^ a b c "Citigroup Center - The Skyscraper Center". Council on Tall Buildings and Urban Habitat. 
  2. ^
  3. ^ Joe Morgenstern (1995), "The Fifty-Nine-Story Crisis", The New Yorker, May 29, 1995. Pages 45–53.
  4. ^ Eugene Kremer (2002). "(Re)Examining the Citicorp Case: Ethical Paragon or Chimera", Cross Currents, Fall 2002, Vol. 52, No 3.
  5. ^
  6. ^ “New York 2000: Architecture and Urbanism Between the Bicentennial and the Millennium,” by Robert A.M. Stern, David Fishman and Jacob Tilove.
  7. ^ Berg, Eric N. (1987-10-03). "Citicorp Selling Part Offers Headquarter". New York Times. Retrieved 2009-09-04. 
  8. ^
  9. ^
  10. ^ Dana Rubinstein (2008), ‘Citigroup Center’ To Become Scintillating ’601 Lexington Ave’, The New York Observer, December 12, 2008.
  11. ^ "Jones Lang LaSalle to Lease Renamed 601 Lexington Avenue"
  12. ^ [1] Boston Properties Announces Second Quarter 2009 Results.
  13. ^ [2] Frank Stella at the Atrium Shops and Cafes at Lexington Avenue and 53rd Street, New York, NY (Formerly Citigroup Center).
  14. ^ BNET Boston Properties to rename 601 Lexington Avenue.
  15. ^ Greer, William R. (October 24, 1982). "Rx for Swaying Skyscrapers". The New York Times. Retrieved 2009-07-25. 
  16. ^ O'Driscoll, Patrick (September 25, 2002). "High-rises remain vulnerable after 9/11". USA Today. Retrieved 2010-04-11. 
  17. ^ Citi Derails Holiday Toy-Train Show in Credit Crunch Bloomberg News, Dec 9, 2008


External links[edit]