The World Trade Center Twin Towers, 1973-2001

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Designed for strength, demolished by terrorists on September 11, 2001

Skyline of New York City, Twin Towers, Taken from New Jersey
Skyline of New York City, Twin Towers, Taken from New Jersey. Photo by Fotosearch/Getty Images

Designed by American architect Minoru Yamasaki (1912-1986), the original World Trade Center consisted of two 110-story buildings (known as the "Twin Towers") and five smaller buildings. The North Tower (1 WTC) was finished in 1970 and the South Tower (2 WTC) was completed in 1972.

About the World Trade Center in New York City:

Architects: Minoru Yamasaki Associates, Rochester Hills, Michigan (design architect); Emery Roth & Sons, New York
Structural Engineers: Skilling, Helle, Christiansen, Robertson, New York
Foundation Engineers: The Port Authority of New York and New Jersey Engineering Department
Architectural Plan Presented: January 1964
Excavation Began: August 1966
Steel Construction Starts: August 1968
Buildings Dedicated: 1973
TV Tower (360 feet) Installed: June 1980 on the North Tower
First Terrorist Attack: February 26, 1993
Second Terrorist Attack: September 11, 2001

The World Trade Center is a living symbol of man's dedication to world peace.
~Minoru Yamasaki, chief architect

Yamasaki studied over a hundred models before adopting the twin tower plan. Plans for a single tower were rejected because the size was cumbersome and impractical. Plans for several towers "looked too much like a housing project," Yamasaki said. The World Trade Center Towers were among the tallest buildings in the world, and contained nine million square feet of office space.

The World Trade Center Twin Towers were light, economical structures designed to keep the wind bracing on the outside surfaces.

Source in Part: The World Trade Center Chronology of Construction, Office of Cultural Education, New York State Education Department (NYSED) at http://www.nysm.nysed.gov/wtc/about/construction.html [accessed September 8, 2013]

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The WTC and Structure of the Twin Towers

Aluminum and steel lattice formed the facade of the New York World Trade Center.
Aluminum and steel lattice formed the facade of the New York World Trade Center. This black and white photo was taken in 1982. Photo © Daniel Stein / iStockPhoto

The World Trade Center construction site closed off one of New York City's north-south streets in 1967—Greenwich Street in Manhattan—to accommodate the proposed seven buildings:

  • WTC 1, the North Tower, had 110 floors
  • WTC 2, the South Tower, had 110 floors
  • WTC 3, a 22 floor hotel
  • WTC 4, the South Plaza Building, had 9 floors
  • WTC 5, the North Plaza Building, had 9 floors
  • WTC 6, the United States Customs House, had 8 floors
  • WTC 7, 47 Floors

On September 11, 2001, terrorists used aircraft to destroy the two tallest buildings.

About the Twin Towers, Designed by Minoru Yamasaki:

  • Tower One was 1,368 feet (414 meters) tall, 110 stories high
  • Tower Two was 1,362 feet (412 meters) tall, 110 stories high
  • Each Tower was 64 meters square
  • Each Tower rested on solid bedrock, the foundations extending 70 feet (21 meters) below grade
  • Height-to-width ratio of 6.8
  • Facades constructed of aluminum and steel lattice
  • Built of a lightweight tube construction with 244 closely spaced columns on the outer walls; no interior columns in office spaces
  • A 80 centimeter tall web joist connected the core to the perimeter at each floor
  • Concrete slabs were poured over the web joists to form the floors
  • Each Tower contained 104 passenger elevators
  • Each Tower had 21,800 windows, over 600,000 square feet of glass
  • Both Towers weighed about 1,500,000 tons together
  • About 50,000 people worked in the Twin Towers
  • Constructed between 1966 and 1973; 3,500 people worked at the site during peak construction; 60 people died during construction
  • Each year, 250,000 gallons of paint were used to maintain the the Towers
  • On August 7, 1974 Philippe Petit used a bow and arrow to assemble a steel cable between the two towers and then he walked across the tightrope. Other stunts included parachuting from the top and climbing from the bottom of the Towers.
  • Almost the same number of murders (19) were committed at the WTC as babies born there (17)

The Twin Towers and the New World Trade Center

After the September 11 terrorist attacks, two trident (3-pronged) columns from the original Twin Towers were salvaged from the ruins. They became part of the exhibition at the National 9/11 Museum at Ground Zero.

Architects also paid homage to the the lost Twin Towers by giving the new skyscraper, One World Trade Center, similar dimensions. Measuring 200 feet square, the footprint of One World Trade Center matches each of the Twin Towers. Except for the spire, the 2014 One World Trade Center is 1,368 feet tall, like Tower One. If you also exclude the parapet, One World Trade Center is 1,362 feet tall, like Tower Two.

Source in Part: The World Trade Center Facts and Figures, Office of Cultural Education, New York State Education Department (NYSED) at http://www.nysm.nysed.gov/wtc/about/facts.html [accessed September 8, 2013]

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The Buildings We Build

A hard-hat worker at the site of the Twin Towers Construction, circa 1970
A hard-hat worker at the site of the Twin Towers Construction, circa 1970. Photo by Archive Photos/Archive Photos Collection/Getty Images

The 16 acre area in Lower Manhattan was meant to be an homage to capitalism and the "center" of "world trade." David Rockefeller had originally proposed developing along the East River, but the West side was chosen—disregarding the protests of displaced businesses bought out by eminent domain. The tall skyscrapers for New York's Financial District would replace the many small businesses that made up "Radio Row" electronics shops. Greenwich Street would be chopped off, disconnecting city neighborhoods largely populated by immigrants from the Middle East, including Syria.

Thousands of construction workers tore down the small businesses and built the World Trade Center superblock beginning in 1966 (see historic construction video from the Port Authority of New York and New Jersey). The chosen design architect, Minoru Yamasaki, may have been conflicted by the values and politics surrounding the vast, high-profile project.

In the Words of American Architect Minoru Yamasaki:

"There are a few very influential architects who sincerely believe that all buildings must be 'strong'. The word 'strong' in this context seems to connote 'powerful'— that is, each building should be a monument to the virility of our society. These architects look with derision upon attempts to build a friendly, more gentle kind of building. The basis for their belief is that our culture is derived primarily from Europe, and that most of the important traditional examples of European architecture are monumental, reflecting the need of the state, church , or the feudal families — the primary patrons of these buildings — to awe and impress the masses. This is incongruous today. Although it is inevitable for architects who admire these great monumental buildings of Europe to strive for the quality most evident in them — grandeur, the elements of mysticism and power, basic to cathedrals and palaces, are also incongruous today, because the buildings we build for our times are for a totally different purpose."

—Minoru Yamasaki, from Architects on Architecture: New Directions in America by Paul Heyer, 1966, p. 186

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Yamasaki, the World Trade Center, and World Peace

The New York State World Trade Center towers viewed from below
The New York State World Trade Center towers viewed from below, before the September 11, 2001 terrorist attack. Photo © 7iron / iStockPhoto

Architect Minoru Yamasaki rejected the European notion of a strong, powerful, monumental architecture. The buildings we build today "are for a totally different purpose," he has said. At the opening of the World Trade Center on April 4, 1973, Yamasaki told the crowd that his skyscrapers were symbols of peace:

"I feel this way about it. World trade means world peace and consequently the World Trade Center buildings in New York...had a bigger purpose than just to provide room for tenants. The World Trade Center is a living symbol of man's dedication to world peace...beyond the compelling need to make this a monument to world peace, the World Trade Center should, because of its importance, become a representation of man's belief in humanity, his need for individual dignity, his beliefs in the cooperation of men, and through cooperation, his ability to find greatness."

—Architect's Statement from Minoru Yamasaki, chief architect of the World Trade Center

Learn More:

Source in Part: The World Trade Center, Office of Cultural Education, New York State Education Department (NYSED) at http://www.nysm.nysed.gov/wtc/about/ [accessed September 8, 2013]