This Day In History: April 4

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The “Twin Towers” of the World Trade Center officially open in New York City. The buildings replaced the Empire State Building as the world’s tallest building. Though they would only hold that title for a year, they remained a dominant feature of the city’s skyline and were recognizable the world over long before they were destroyed in a terrorist attack in 2001.

Planning, designing and clearing space for the World Trade Center took over a decade. The New York State Legislature originally approved the idea in 1943, but concrete plans did not materialize until the 1960s. The deal that created the new complex, of which the Twin Towers would be the centerpiece, also included the creation of the Port Authority Trans-Hudson Corporation, or PATH, to operate the trains which entered Manhattan from New Jersey on what was to become the grounds of the WTC. Architect Minoru Yamasaki drew inspiration from Arabic architecture for the towers’ design. In order to efficiently move people up and down the 110-story towers, Yamasaki and his team developed the concept of express elevators—based on the New York City Subway’s system of express and local trains—that traveled directly to “sky lobbies” on the 44 and 78 floor, from which “local” elevators ran to neighboring floors. The first tenants moved into the North Tower in December of 1970, with the official opening of both buildings taking place over two years later.

The towers’ construction ended the Empire State Building’s 41-year run as the tallest building in the world. They were replaced by Chicago’s Sears Tower the following year, an indication of the rising trend of supertall construction. The World Trade Center dramatically altered the New York skyline and the cityscape of Lower Manhattan. As such, they were often used as a shorthand for the area in visual media, and were frequently included in establishing shots of films set in New York. Though most of the World Trade Center was occupied by office space, the Top of the World Observation Deck on the South Tower became a popular tourist destination, as did the North Tower’s Windows on the World restaurant, which featured its own wine school.

The towers were first targeted by terrorists in 1993, when a bomb exploded in the garage under the North Tower, killing six and injuring over 1,000. The Twin Towers were destroyed, and were the site of the vast majorities of the casualties, on September 11, 2001, a final chapter that has since overshadowed the rest of the World Trade Center’s story. The building that replaced them, One World Trade Center, was completed in 2014.