Height: 1,368 and 1,362 feet (417 and 415 meters)
Owners: Port Authority of New York and New Jersey
Architect: Minoru Yamasaki, Emery Roth and Sons consulting
Engineer: John Skilling and Leslie Robertson of Worthington, Skilling, Helle
Ground Breaking: August 5, 1966
Opened: 1970-73; April 4, 1973 ribbon cutting
The World Trade Center is more than its signature twin towers: it is a complex
of seven buildings on 16-acres, constructed and operated by the Port Authority
of New York and New Jersey (PANYNJ). The towers, One and Two World Trade Center,
rise at the heart of the complex, each climbing more than 100 feet higher than
the silver mast of the Empire State Building.
Construction of a world trade facility had been under consideration since the
end of WWII. In the late 1950s the Port Authority took interest in the project
and in 1962 fixed its site on the west side of Lower Manhattan on a superblock
bounded by Vesey, Liberty, Church and West Streets. Architect Minoru Yamasaki
was selected to design the project; architects Emery Roth & Sons handled
production work, and, at the request of Yamasaki, the firm of Worthington, Skilling,
Helle and Jackson served as engineers.
The Port Authority envisioned a project with a total of 10 million square feet
of office space. To achieve this, Yamasaki considered more than a hundred different
building configurations before settling on the concept of twin towers and three
lower-rise structures. Designed to be very tall to maximize the area of the
plaza, the towers were initially to rise to only 80-90 stories. Only later was
it decided to construct them as the world's tallest buildings, following a suggestion
said to have originated with the Port Authority's public relations staff.
Yamasaki and engineers John Skilling and Les Robertson worked closely, and the
relationship between the towersi design and structure is clear. Faced
with the difficulties of building to unprecedented heights, the engineers employed
an innovative structural model: a rigid "hollow tube" of closely spaced
steel columns with floor trusses extending across to a central core. The columns,
finished with a silver-colored aluminum alloy, were 18 3/4" wide and set
only 22" apart, making the towers appear from afar to have no windows at
Also unique to the engineering design were its core and elevator system. The
twin towers were the first supertall buildings designed without any masonry.
Worried that the intense air pressure created by the buildingsi high
speed elevators might buckle conventional shafts, engineers designed a solution
using a drywall system fixed to the reinforced steel core. For the elevators,
to serve 110 stories with a traditional configuration would have required half
the area of the lower stories be used for shaftways. Otis Elevators developed
an express and local system, whereby passengers would change at "sky lobbies"
on the 44th and 78th floors, halving the number of shaftways.
Construction began in 1966 and cost an estimated $1.5 billion. One World Trade
Center was ready for its first tenants in late 1970, though the upper stories
were not completed until 1972; Two World Trade Center was finished in 1973.
Excavation to bedrock 70 feet below produced the material for the Battery Park
City landfill project in the Hudson River. When complete, the Center met with
mixed reviews, but at 1,368 and 1,362 feet and 110 stories each, the twin towers
were the world's tallest, and largest, buildings until the Sears Tower surpassed
them both in 1974.
On the 11th of September 2001 The World Trade Center collapsed becaused it was
struck by two civillian airplanes.