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February 5th through May 5th, 2002 An exhibition by The Skyscraper Museum at The New-York Historical Society website.

This tribute to the Twin Towers examined the history of the complex in its conception, design, and construction from the 1960s through the mid-1970s -- and its destruction on the morning of 9/11. Curated by Carol Willis, the director of The Skyscraper Museum, the exhibition WTC emphasized the monumental scale of the Twin Towers and explored their place in the postwar transformations of Lower Manhattan.

In the summer of 2001, The Skyscraper Museum decided to collect material on the planning, design, construction, and operation of the World Trade Center. To initiate this project, we organized a series of lectures for the fall that would bring together key members of the teams that created the Twin Towers more than three decades ago. The programs were scheduled for October in the Horizon Suite of Windows on the World in Tower 1. This exhibition evolved from that tragically postponed project.

The mission of The Skyscraper Museum is to display and interpret stories of highrise buildings and their urban environment. In the months after 9/11, we hastened to gather a range of artifacts to pay tribute to the towers, to illustrate their monumental scale, and to represent the diverse material the museum plans to collect. Most came from private hands, either companies or individuals.

Many deserve thanks for help in mounting this exhibit.

Installation Views

On entering the gallery, the visitor caught sight of the architects' original ten-foot model of the Twin Towers and other images and artifacts of their construction, as well as the mural-size photographs of their destruction in the rear of the space. The text on the wall at the right appears on the next screen.

Venue: The New-York Historical Society

The Skyscraper Museum was displaced from its temporary gallery in Lower Manhattan on 9/11. As a result, we wondered how to find a way to respond to the crisis and questions of a story so central to our institution's identity. WTC: Monument was presented in the galleries of The New-York Historical Society from February 5th through May 5th, 2002. We are extremely grateful to President Kenneth T. Jackson for offering us their galleries for that purpose. In addition, the Society's trove of treasures and the generous assistance of its staff greatly enriched the exhibit.


Intro image


New York in the 1960s was a city on the rise, and no project symbolized the confidence in "bigger is better" than did the World Trade Center. On completion in 1971 and 1973, the Twin Towers were both the tallest and the largest buildings in the world. Innovative engineering carried the structures to 110 stories, multiplying floorplates of nearly an acre into more than four million square feet of office space in each tower.

The scale of the buildings was in keeping with the enormity of changes in postwar New York, where modernity mattered more than history. Gleaming glass skyscrapers created new corporate corridors in a surging midtown office market. Downtown, though, choking congestion, obsolete piers, and aging buildings - whether the remains of the 19th-century waterfront or the last generation of classic Wall Street towers - signaled decline. In the 1960s and 1970s, planners and politicians envisioned Lower Manhattan transformed by an aggressive policy of urban renewal that would modernize physical conditions and reinforce the evolution from port to paperwork. The design of the WTC asserted the ambitions of the era to reshape both Lower Manhattan and the skyscraper as a building type.

The tragedy of 9/11 separates forever a "before and after" in New York's romance with its skyline. Nothing about the World Trade Center will ever be as acutely remembered as its destruction, but there is much to understand in the story of its creation that can inform and inspire our future actions. The reality of what replaces the Twin Towers will be a reflection of the powerful new history that has overtaken the site and, one hopes, of a new form of urban renewal.


Problems and Plans

Lower Manhattan in the Sixties was a mature business district trapped in the fitments of an earlier age. A corset of finger piers bounded the island's edge, constraining growth. The downtown waterfront had been rendered obsolete, first by larger ships with deeper drafts, and from the late 1950s, by containerization which drove shipping to relocate to the vast, vacant expanses of the New Jersey lowlands. Of 51 piers, only 18 were active in 1966. The remnants of the working waterfront still exaggerated congestion, as cargo was unloaded onto the street. Elevated highways intended to improve traffic flow further segregated the public from the rivers.

The reclamation and reinvention of the waterfront became a chief focus of plans for Lower Manhattan. Strategies included demolishing the decaying piers and enlarging the island, either by landfill, as at Battery Park City, or by platforming over the water, as intended, but not executed, on the East River. The low-rise, mostly 19th-century mercantile buildings that occupied the area adjacent to the piers were slated for demolition under the city's urban renewal policy. In their place, planners envisioned development zones of modern office buildings and new residential neighborhoods. The two business magnets were the World Trade Center complex and the South Ferry and Water Street district.

Image Credits:

Top image:
Lower Manhattan, August 3, 1956
Thomas Airviews, Lower Manhattan
Silver-gelatin print, 8 x 10 in.
Collection of The New-York Historical Society

Bottom image:
Lower Manhattan, May 5, 1976
Thomas Airviews, Lower Manhattan
Silver-gelatin print, 8 x 10 in.
Collection of The New-York Historical Society


Model: The Lower Manhattan Model

This extraordinary model of Lower Manhattan was commissioned by the Downtown-Lower Manhattan Association, a group of business leaders led by David Rockefeller, to promote, in cooperation with the City Planning Commission, various plans for the revitalization of Lower Manhattan. The model accurately represents existing buildings in gray and beige and distinguishes proposals, generally in white.

Some schemes represented were ultimately realized, such as the World Trade Center and Battery Park City (over time, and with a different configuration of housing and office buildings), while others remained dreams. Traffic congestion was a major frustration and fixation of the planners. The model includes a range of ambitious and expensive plans, such as the 1966 West Side Depressed Expressway, a proposal that predated "Westway," and the Lower Manhattan Expressway, envisioned by Robert Moses, that was to slice across the island on Broome Street. Also of note is the creation of a park and pedestrian precinct around the government buildings of the civic center that was to have been made possible by tunneling the traffic under the site.

The model was created by Theodore Conrad (1910-1994), a master craftsman who initiated a revival of models as important design tools. It was acquired by The New-York Historical Society in 1998 after it was displayed in the first exhibition of The Skyscraper Museum, "Downtown New York."

Model Credits:
Theodore Conrad
Model of Lower Manhattan [1968-1970]
Painted wood, plastic, 108 x 96 in.
Collection of The New-York Historical Society

Lower Manhattan Aerial Photographs

The first room also featured a group of vintage Thomas Airviews of Lower Manhattan from the Society's collection that record the transformation of the district from the 1940s through the 1970s. These black-and-white photos, printed from 8 x 10 negatives, reveal both extraordinary detail of individual buildings and, over time, document panoramas of change. The most striking difference over the decades takes place at the island's edge where the dozens of finger piers that lined both riverfronts disappeared through removal, collapse, or under landfill. The Thomas Airviews chronicle the clearing and excavation of the World Trade Center site and the progress of the towers' construction. Other photographs in this section capture lost views from ground level of the Washington Market urban renewal area just north of the Twin Towers.

Reproductions are allowed ONLY by signing a Permission Agreement. There is no right to reproduce this image without a Permission Agreement. All Reproductions must be accompanied by this credit line:

Copyright: Collection of the New-York Historical Society


A Modern Downtown

Downtown's other major problem was the exodus of corporate headquarters and jobs to midtown and beyond. Statistically, Lower Manhattan held its status as the nation’s largest central business district through the mid-1940s, but in the 1950s and '60s, an array of signature glass towers on Park Avenue and Avenue of the Americas established the International Style and the "tower in the plaza" as the image of modernity and corporate success.

Except for the elegant new headquarters of Chase Manhattan Bank, completed in 1961, downtown's dignified but aging office stock consisted primarily of buildings erected from the 1900-1930s, built before air conditioning and fluorescent lighting. In the congested but still prime core around Wall Street, construction was exceptionally complex and expensive. Plans for new office development therefore focused on the low-rise buildings at the edges of the historic core and on the waterfront where buildings were low-rise and of lower valuation. The targeted expansion districts were the World Trade Center, developed by The Port of New York Authority, and a newly widened Water Street, where private investment financed big, bulky towers with zoning bonuses and other incentives from the City.

Image Credit and Description:

Thomas Airviews, Lower Manhattan
Aerial view of Wall Street and financial district
May 18, 1960
Silver-gelatin print, 8 x 10 in.
Collection of The New-York Historical Society

The extraordinary density of skyscrapers and narrowness of streets in the historic core of the financial district are especially clear in this photograph, which features at the center the new 60-story headquarters of Chase Manhattan Bank before its spacious plaza was completed.


A World Trade Center and The West Side Site

The next section focused on the client, then known as The Port of New York Authority [now The Port Authority of New York and New Jersey (PANYNJ)], the site selection, and the architectural commission, won by Minoru Yamasaki. On display are many earlier planning reports and study proposals for a trade center and design proposals for different building solutions. The chief attraction of this section is the original presentation model of the complex from the office of Yamasaki Associates.


A World Trade Center

The idea of a World Trade Center first appeared in the late 1950s for a site on the East River. Promoted by the Downtown-Lower Manhattan Association (DLMA), a powerful organization of business interests led by David Rockefeller of Chase Manhattan Bank, the World Trade complex was to centralize the many aspects of shipping and merchandising of imports and exports and thus to bolster the declining fortunes of the Port of New York.

With the endorsement of City Hall, the DLMA enlisted the Port of New York Authority, as the bi-state agency was then known, as the best potential developer for a "World Trade and Financial Center." In March 1961, the Port Authority issued a report favoring the plan. The project conformed only obliquely to their basic mission which, when established in 1921, was to improve terminals in the port and related transportation facilities. At the time, though, the Port Authority was flush with the revenues of the bridges, tunnels, and regional airports. The City reluctantly agreed to allow the Port Authority to become the owner and developer of the World Trade complex, ceding both control over the land and the annual property-tax revenues.

The images to the left are taken from the document "World Trade Center; A Proposal for the Port of New York".


The West Side Site

In the fall of 1961, the plans for the Trade Center shifted to the west side, on the Hudson River waterfront. New Jersey officials had resisted approving a Port Authority project that was unconnected with their state's development and transit needs. Delays followed, and a Port Authority planner then suggested the center be shifted to the west side, where it could be linked to the bankrupt Hudson and Manhattan Railroad, which carried commuters from Newark and Hudson County. In the spring of 1962, the two states approved the new location, and the Trade Center legislation was joined with the Port agency's purchase and modernization of the rail line (now PATH).

The new site included the Hudson and Manhattan Terminal, a pair of 22-story office buildings on Church Street between Cortland and Fulton, which on completion in 1909 constituted - like the later Twin Towers - the largest office complex in the world.

Another important part of the political solution to the west side site was the agreement with New York City to use the excavated dirt of the Trade Center foundations as landfill for the first 23 acres of Battery Park City.


Model: The Emery Roth Model

This massing model shows the Trade Center complex and the blocks north to Chambers Street. It was made by Joseph Zevlin Models for the office of Emery Roth and Sons, who were associated with Yamasaki on the project. The context shows existing buildings on the city blocks to the north of the site and is notable for the clear outline of the low-rise building just to the right/ north of the Trade Center, on the site that became World Trade Center 7, which collapsed on 9/11.

World Trade Center model, 1:1000
Liberty Street to Chambers Street, Church Street to The East River
28 x 37 x 25 in.
Joseph Zevlin Models for the office of Emery Roth and Sons, [1971]
On loan from the collection of Jordan Auslander



In 1962, after a series of design studies developed with a team of prominent New York architects, the Port Authority gave the commission for the World Trade Center to Minoru Yamasaki of Troy, Michigan. It was a surprising choice, since the tallest structure Yamasaki had designed previously was a 22-story highrise in Seattle. For the expertise necessary to lay out efficient floorplans and core and to produce the thousands of construction drawings required, the Port Authority hired as associated architects New York's most prolific skyscraper firm, Emery Roth and Sons.

The program for the complex was simple: ten million square feet of office space. There was no prescribed number, height, or configuration of the buildings on the site. After exploring nearly a hundred variations, Yamasaki decided on two identical 100-story towers, set askew, as the centerpiece of a five-acre plaza framed by lowrise buildings. Each tower had a footprint 209 feet square, making the floors an acre in area.

In addition to the formal gesture of the sheer, slender towers, the other key architectural decision was to employ an exterior, load-bearing wall with the columns expressed as continuous verticals, soaring a quarter mile from the plaza into the sky. The columns were 18 inches wide and so closely spaced, with recessed windows of only 22 inches, that the facade appeared to be almost solid. The aesthetic was the opposite of the elegant glass boxes of the era such as Lever House, the Seagram Building, or 1 Chase Manhattan Plaza.


Model: The Yamasaki Model

This original presentation model from the office of architect Minoru Yamasaki of Troy, Michigan was produced in 1971 to illustrate how the World Trade Center would look when finished in 1974. It is the only surviving architectural model; two others of a smaller scale were destroyed in the Twin Towers when they fell.

Architectural models are constructed to provide a client with a view of how a proposed project will look upon a given site on completion. Because of size and fragility of materials, models are difficult to store and maintain and are often badly damaged or destroyed over time. After this exhibition, the model will undergo conservation and be displayed on extended loan at the new home of The Skyscraper Museum in Lower Manhattan. The conservation has been made possible by a generous grant from the Museum Loan Network.

Model Credits:
Yamasaki and Associates
World Trade Center presentation model, 1971
Plastic on wood base, plaster, paper
On loan from the Prints and Drawings Collection, The Octagon, the Museum of the American Institute of Architects, Washington, D.C.

Image Credit:
Tony Vaccaro
Yamasaki and WTC model, 1969-70, reprint
Courtesy of the photographer Tony Vaccaro
Minoru Yamasaki, the architect of the World Trade Center, sits at the far right and poses with other members of Yamasaki and Associates in their office in Troy, Michigan.


The World's Biggest Buildings

The competition for the title of world's tallest building is a perennial headline grabber. Far less attention is paid to the issue of the largest building, measured by area of office space. The Twin Towers were at the time of their completion in 1971 and 1973, the biggest buildings in both categories. They were surpassed in 1974 by Sears Tower, the only single tower to exceed them.

To be both big and tall was a phenomenon of the 1960s, the apogee in the century's evolution of skyscraper size. The same "can-do," competitive spirit that fueled the Space Race and moon shots inspired architects and engineers to explore new structural systems in a group of 100-story (plus) towers, including the WTC and John Hancock and Sears in Chicago. Signature skyscrapers justified their great height in part by publicity value. Other bulky blocks of the period satisfied their owners with high rental income, as at One New York Plaza and 55 Water Street in Lower Manhattan, which contained more than 2 and 3 million rentable square feet, respectively.

Recent spires have been arguably taller, but never as large in gross rentable area as the superjumbos of the Sixties.



The achievement of the Twin Towers depended upon innovative engineering. As both client and construction manager, the Port Authority engaged in a program of research and analysis that sought efficiency for the sake of economy and also for the intelligence of the engineering solutions. There were several principal areas of innovation:

The Twin Towers were the first supertall buildings to use "tube" construction, a structural system in which the outside walls act as a thin-shell or tube, cantilevering from the foundations to resist hurricane winds and earthquakes and to stabilize the core against lateral buckling. The system eliminated the need for a conventional rigid-frame, reduced the story height to 12 feet, and allowed column-free space of a 60-foot clear span, with less steel and a lower story height than is found in most 50-story buildings.

Extensive use of wind tunnel testing to analyze the aeroelastic behavior of the structural system and pressures on the cladding was used for the first time in America. This study was coupled with an exhaustive statistical analysis of building motion, as well as a physiological study of human sensitivity to transverse oscillation, or sway.

The prefabrication of structural components was developed to a point unprecedented in high-rise buildings, and the detailed design for most of the steel work was presented to manufacturers for the first time in digital format on IBM punch cards.

For the excavation of the foundations of the 16-acre site, known as "the bathtub," the method of slurry-wall construction was used for the first time in the United States.

Other firsts included: the use of damping devices incorporated into the structural system and the development of a new partition called "Shaftwall" that eliminated masonry in the building core.


The Wind Tunnel Model

Wind effects on tall buildings can be accurately predicted by three kinds of tests in a laboratory wind tunnel. Special, highly accurate models are built to represent the building's form and nearby surroundings, often at a scale of 1:400.

This is the original "pressure tap" model for the World Trade Center. It measured local pressures on the facade by using hundreds of tiny tubes that connect to sensors.

There are two other types of models: a "force balance" model that measures overturning of the entire building as wind gusts strike randomly; and an "aeroelastic" model which also measures overturning, but includes the effect of the natural rate of rhythmic rocking back and forth, known as the building's period.

Model Credits:
Loan from Leslie E. Robertson and Associates



The section on construction featured a dramatic 18-minute film titled "Building the World Trade Center" made by the Port Authority in 1983 from footage shot during the original construction. The color film documents and narrates the project from the clearing of site through the excavation, foundations, and steel hoisting and erection. The finished building is toured from bottom to top, including gazing out from now-lost vistas on the roof. The remainder of objects in this section were copy prints of photographs of construction workers on the job taken by the Port Authority's staff, as well as other photographs by individuals who have recently donated their prints to the Museum.



These photographs by Grant Peterson, taken from a Soho window on the crystal clear morning of September 11, record the tragedy as witnessed by one person from a distance. They represent experiences of eyewitnesses who, in this densely populous region, watched the events unfold from perhaps a million perspectives. In their sharp focus and exceptional enlargement, these photographs force an encounter with the reality of that morning we will never forget.

Grant Peterson/Watch
Artist's statement:

"On September 11th, I was renting a studio on the eighth floor of 568 Broadway in Soho for a photo shoot. My 4 x 5 camera was set up, and when I learned of the attack on the World Trade Center, I trained my camera on the lower Manhattan skyline some two miles distant and had the opportunity to shoot the Twin Towers as they burned and fell. Three days later, I developed the film and to my amazement found that the series documents the historic moments in extreme detail and clarity.

"My series of four prints of that morning record each tower at pivotal moments of change: 9:08 two towers burning; 9:58 south tower falling; 10:28 the north tower falling; 10:29 no towers standing. These prints are epic in subject, scale, and production. They are scanned and printed at over 2 gigabytes and enlarged to 58 X 106 inches, making them among the largest photographs ever printed at this level of clarity.

"These prints are an attempt to understand the size, scale, and immediacy of the experience of those who watched the towers fall in the midst of Manhattan."


Photographer: Grant Peterson
Imaging and retouching: Leo Chapman
Printing and finishing provided by: Autograph, John Pecora and Dick McKie
Coordinated by Steve Boulter and Improved Technologies, Michael Pelletier
Substrate: ChromaZone: Glossy White Film
Ink: ChromaZone Ultra Gamut dye ink
Camera: Sinar 4X5
Film: Fuji Astia 4X5

Special thanks to Bruce Mitchell, Fujifilm and Jim Reed, Sinar Bron

The installation photograph at right was taken by Grant Peterson of Maddie Peterson, his daughter.


Curator: Carol Willis

Installation design: Lynne Breslin

Graphic design: Pentagram

Leslie E. Robertson, structural engineer of the World Trade Center shared his knowledge and original records. Through the summer of 2001, members of the Port Authority's World Trade Department, Alan Reiss and his staff, offered information and tours of the buildings: we especially remember Frank De Martini, who died in Tower 1. Sherry Birk of The Octagon Museum in Washington D.C. offered the Yamasaki model for the exhibition. Others who donated or loaned photographs or other material to the museum include Grant Peterson, Jordan Auslander, Bettina Cirone, Andrew Dolkart, Flo Fox, Sidney Frigand, Donald Lokuta, Tony Vaccaro, and Paul Willen. Photographic enlargement, printing, and finishing provided by Autograph, John Pecora and Dick McKie, and coordinated by Steve Boulter and Improved Technologies, Michael Pelletier.

WTC: MONUMENT is made possible with generous support from The Bodman Foundation, The Liman Foundation, The Henry Luce Foundation, The Philip Morris Companies, Mueser Rutledge Consulting Engineers, Otis Elevator, and Ms. Jacqueline Fowler. The exhibitions and programs of The Skyscraper Museum are supported by public funds from the New York State Council on the Arts, a State Agency.