By the time this aerial view of the World Trade Center was taken in the late 1970s, the twin towers had already been surpassed as the world's tallest buildings. Photo: Peter J. Eckel/AP
1970: Construction workers place the highest steel on the highest building in the world. New Yorkers will first hate it, then get used to it and eventually mourn its destruction.
The massive project was conceived in the 1950s to energize lower Manhattan. Architect Minoru Yamasaki worked in conjunction with Emery Roth and Sons to design twin towers 110 stories high.
Ground was broken Aug. 5, 1966, and steel construction began in August 1968. The North Tower topped out at 1,368 feet (some sources say 1,353 feet) Dec. 23, 1970. Ribbon-cutting took place April 4, 1973.
The twin towers knocked New York City’s own Empire State Building (1931, 1,250 feet) off the top of the list of the world’s tallest buildings, but lost out in 1974 to Chicago’s Sears Tower at 1,451 feet. The twin 1,483-foot Petronas Towers in Kuala Lumpur, Malaysia, surpassed Sears in 1998, only to be overtaken by Taipei 101 in Taiwan at 1,667 feet in 2004. Burj Khalifa (formerly Burj Dubai) in the United Arab Emirates is the current leader, at 2,716 feet.
With an acre of rentable space on each of the upper floors of each tower, the WTC’s 110 stories were ocupied by about 50,000 people. The South Tower had an observation deck on its 107th floor, offering views for 45 miles in all directions, skies permitting.
The architects and engineers had solved a number of problems with great ingenuity. To keep the nearby Hudson River from flooding its foundations, the buildings were constructed in a vast concrete case, called the Bathtub. A central core in each tower carried the dead (or gravitational) weight of the building’s materials, while light walls were designed to withstand the force of wind on a tall, giant building.
