Associate Architect
Emery Roth & Sons
Structural Engineer
Leslie E. Robertson Associates
Construction Company
Tishman Realty & Construction Company
Designed in
Built in
415 - 417 m
Built-up Area
930.000 m²
Manhattan, New York, United States
Some parts of this article have been translated using Google’s translation engine. We understand the quality of this translation is not excellent and we are working to replace these with high quality human translations.


The Twin Towers of New York, designed by Minoru Yamasaki , were part of the World Trade Center, a complex of seven buildings in the Financial District Manhattan. These steel monoliths with 110 stories and 417 meters high, although one measured 415, changed the skyline of the city and were the highest in Manhattan at the time of building completion and the fourth in the world rankings, behind of the Petronas Towers to Malaysia ( 452 m), the Sears Tower to Chicago ( 443m ) and Jin Mao Tower to China ( 421m ).

Begun on August 5, 1966, the Towers were completed and officially opened on April 4, 1973, although the work does not really end until 1975.

The September 11, 2001, the Twin Towers were destroyed by a terrorist attack that crashed a plane 767 in each of the buildings. The tower one, two and seven complex collapsed and the rest was demolished after being damaged beyond repair.


The World Trade Center was conceived in early 1969 by the Association of Lower Manhattan Development, aiming to revitalize the seedy area occupied primarily by electronic stores. The chairman of Chase Manhattan Bank, David Rockefeller, founder of the development association, and his brother, New York governor Nelson Rockefeller, pushed for carrying out the project, insisting it would benefit the entire city.

In 1962, the Port Authority of New York and New Jersey began plans to build the center.


The Twin Towers were built in the World Trade Center complex occupied 6.5 acres near Hudson River in the heart of the Financial District of Manhattan. Grouped around a central square and bounded by Vesey Street to the north, Church Street to the east, Liberty Street to the south and West Street on the west, three blocks north of the New York Stock Exchange.

Under this complex, access to the train station to Jersey City, and three stations were subway lines.


“… The purpose of architecture is to create an atmosphere in which man can live, work and play at the same time… ”

These are words of Minoru Yamasaki who with the design of the Twin Towers posed to the Big Apple and all the citizens of New York coexistence on arrogance, represented by the duality of the two towers.

These became the new image of the city, the gateway transmitting a message of brotherhood for which had to be some time before it came to be captured by the popular intuition.

From the beginning the project was to be impressive, but it was Yamasaki who proposed to turn the concept of a complex of buildings in the tallest structure in the world and who devised the proposal meet almost any surface 930,000 m², in the project office in two identical towers.


The Twins, Torre Sur (South Tower) and Torre Norte (North Tower), Torres offered 4000 square meters per floor for offices, approximately 930,000 m². Most are surface was occupied by offices of 28 different countries, but also had exhibition halls, auditoriums, restaurants, a hotel with 250 rooms, equipment rooms and service


The three vertical sectors where the towers were determined by dividing elevator systems.

To plant were 41 and 74 Express lifts, with lobbies at those levels, connecting with a second network of elevators that let the traveler in other plants, thereby avoiding some stops and making the climb in less time. Also there was a direct lift from the first floor to the 107, without any stop.

South Tower

It was occupied by bank branches, offices telecommunications, Sun Microsystems (technology), units of the New York Stock Exchange on floors 28 and 30, Siemens Telecommunications, insurance companies and investment, publishing, Department of Finance and Treasury of New York and veranda on the 107 and 110 plant.

  • Viewing deck

From this apartment 107, where a restaurant offering sweeping views of the city, you could access the terrace which was in the 110th floor via escalators. It was one of the few places open and accessible to the public.

” Top of the World ” as they knew this was a lookout platform both indoor and outdoor observation featuring a 360 º view of the city of New York and over a distance of 80 km with clear skies.

There was also in this area gift shops, an information and food stalls.

North Tower

In this tower had their offices the Port Authority of New York occupying several floors, insurance companies, an investment company, the company AT & T Telecommunications, Law Firms, Channel Four (NBC ) Television, a restaurant on the 107th floor and the CNN on the 110th floor.

Underground Levels

There were seven underground levels including amenities, parking with 2000 spaces, shops, a railway station and several subway.


The structure of both towers corresponded to the system “tube in tube” instead of distributing structural columns within the building, unfolding brackets connecting the inner tube, central core, with the perimeter edge, outer tube.

  • Inner tube

The first tube, the ” inner tube ” was formed by a hollow interior of 27x41metros surrounded by a mesh of 48 steel columns spaced one meter between them that ran from the foundation to the top of the building, reinforced concrete, forming the central core of the building where the stairs, elevators and wiring were located, thus creating a rigid sturdy central column that supported most of the vertical loads.

The entire perimeter surrounding the central core was played with dried modules. The intermediate space between the central core and the perimeter fence, no columns was vertically segmented by the slabs of plant consisting of thin concrete slabs 10 cm thick on a sheet metal decking strapping steel, which in turn is supported in a slender trusses linking the core to the perimeter at alternate columns framing. These trusses are supported externally on small brackets welded to the front, and inside the main columns in the core. This served forged stiffeners structure and acted as diaphragms hardened outer side walls against wind pressures, while its elastic support truss perimeter helped reduce the feeling of rocking on its occupants, typical of buildings as high.

  • Outer tube

The second, the ” outer tube ” was formed by 224 steel columns that were distributed around the perimeter of the front from top to bottom forming a structural mesh coated with a skin of aluminum alloy whose pieces are assembled one by one. The steel columns were reinforced with a lattice vierendeel whose vertical bars connecting the upper and lower ends rigidly, without resorting to the diagonal bars.

The Twin Towers endured higher oscillations at 4 110 meters in the ground, supported by its structure and 63.5 meters wide exercising as a lever arm offset the stresses and strains caused by high winds.

The slabs of each plant were supported on the perimeter columns and in the communication area.


Surrounding the steel structure of the towers 43,600 windows, 45 cm wide were also distributed. The architect explains this small measure in the many windows of the building in relation to its acrophobia… ” Many times I have gone to the top floor of a building and I pushed her nose against the glass to see the square below. That I can not do in a building with glass from floor to ceiling and amounts that are, say, five feet from each other, because they have much experience in skyscrapers, still suffer from acrophobia “…


A pit of 55 square kilometers that were filled with iron columns 10 meters high rock stuck in the underground city was needed.

To have 65,000 square meters required the entire building complex was necessary to eliminate five blocks in the area and demolish 164 buildings. The preparation required a trench excavation and removal of 1.2 million cubic meters of earth, which were used to create 23.5 acres of firm along the Hudson River and land became part of Battery Park City in lower Manhattan.

Prior to the demolition was necessary to make a large wall of reinforced concrete reinforced leading down to the rock layer where you should set the foundation and avoid the leakage of water from the river on land in the eighteenth century were covered by the Hudson.

This underground wall was built section by section, 90 cm wide each, making the material removed and pumping bentonite in its

subsequently to enter inside preassembled frames made ​​of steel and reinforced concrete fed. Thus it was possible to create a large tub which allowed to keep working inside. During the peak period in the construction of the towers 10,000 people worked there


  • Roof Height : Tower 1: 417m – Tower 2 : 415m
  • Last Plant height: Tower 1 : 313m – Tower 2 : 411m
  • Number of floors : 110
  • Width: 63.5 m
  • Number of lifts: 104 in each tower
  • Free area per floor: 4020m


In its construction 180 thousand tons of steel, 4,800 miles of electrical connections, 325,000 m³ of concrete, 300,000 m² of glass surface corresponding to 43,600 windows, 198 elevators with an average capacity of 55 people and 71 escalators were used

  • Steel

The steel used in the Twin Towers was of low carbon alloy of iron and extensively (mainly iron). Low alloy steel was used because the beams can be thinner without decreasing its strength and can thereby obtain more useful area. The melting point of this steel is around 700 th

  • Asbestos

This material consists of several minerals and hydrous silicates of magnesium is highly toxic to inappropriate conditions. It was used in some systems of the Twin Towers as pipes or isolations

  • Elevators

The 104 elevators in each tower, 98 staff and 6 lifts, daily carrying 40,000 permanent employees who had their offices in the towers, plus the many tourists visiting the building each day.

One of the elevators leading from the ground floor to floor 107 without any stop, the tour performed in 58 seconds, at a speed of 40km / h.

Fireproof insulation *

The building Empire State with its traditional, rigid and heavy masonry creates a fire resistant while offering superior wind structure. The Twin Towers with its lightweight structure had more roll angle in response to the wind and fireproof insulation involved a fire resistant foam which were protected by spraying on them, the main structure columns and perimeter.





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