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Steel workers Adam Cross (R) and Steven Cross maneuver a steel column into place on the 100th story at the top of One World Trade Center to make it New York City's tallest building on April 30, 2012 in New York City. One World Trade Center is being built to replace the twin towers destroyed in the Sept. 11 attacks. It reached just over 1,250 feet, making it just taller than the observation deck on the Empire State Building.
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Two construction workers on the 71st floor of One World Trade Center look at a view of the New York skyline, including the Empire State Building.
Spencer Platt / Getty Images
The new One World Trade Center building, which is under construction on the site of the destroyed original World Trade Center, is viewed on April 30, 2012 in New York City. One World Trade officially surpassed the height of the Empire State Building today to become New York City's tallest building. With its unfinished frame the building stands at a little more than 1,250 feet high. Referred to as the "Freedom Tower," it isn't expected to reach its full height for at least another year, when it will likely to be declared the tallest building in the United States and the third-tallest in the world.
See more images of the World Trade Center in PhotoBlog, including this interactive view from the 69th floor shot by msnbc.com's John Makely.
On Monday, the World Trade Center surpassed the height of the top floor of the Empire State Building. When it's completed, the tower will eventually rise 1,776 feet high. NBC's Harry Smith reports.