One World Trade Center in New York will officially be the United States' tallest building when completed, beating out Chicago's Willis Tower. It was recently decided that the 408-foot needle atop the building would be counted in the total height of the tower. See how One World Trade Center stacks up against other tall buildings.
British Prime Minister David Cameron and his wife look over an artist's rendering of the building during a tour of the 20th floor on March 15.
The building currently has 100 floors and stands 1,244 feet tall.
When all 104 stories are completed by 2014, 1 WTC will stretch 1,776 feet into the Manhattan skyline. Here's how it will stack up to the world's tallest buildings.
Burj Khalifa, also known as Burj Dubai or Dubai Tower in the United Arab Emirates, is the tallest building in the world at 2,717 feet tall.
A massive 60-foot spire makes Taipei 101 Tower in Taiwan the third-tallest building in the world at 1,667 feet.
A trapezoid-shaped opening near the top reduces wind pressure on the world's fourth-tallest tower, the 101-story (1,614 feet tall) Shanghai World Financial Center in China.
The International Commerce Centre in Kowloon, Hong Kong, comes in at No. 5, at a height of 1,588 feet and 108 stories.
Tall spires atop the Petronas Towers in Kuala Lumpur, Malaysia, make them the sixth-tallest (tied) at 1,483 feet.
China's Zifeng Tower, which opened in 2010, comes in at No. 7 on the list, rising to a height of 1,476 feet.
The Willis Tower, formerly known as the Sears Tower, was the tallest building in the world when it opened in 1974 and retained that title until the Petronas Towers opened in 1998. Today, it's the eighth-tallest in the world and the tallest in North America at 108 stories and 1,451 feet. One World Trade Center became the tallest structure in North America when a spire installed on the top topped it out at 1,776 feet, but the New York building is still under construction.
The Guangzhou West Tower, located in Guangzhou, China, is the world's 10th-tallest building, coming in at 1,439 feet and 103 stories.
America's current second-biggest building is located just blocks away from it's tallest. The Trump International Hotel and Tower, which opened in Chicago in 2009, rises to a height of 1,389 feet and 98 stories, making it the world's 11th-tallest building.
The towering Jin Mao Building in Shanghai, China, reflects traditional Chinese architecture and rounds out the top 10 list at 1,380 feet, but it's spot on the list won't last long.
The Kingkey 100, scheduled for completion in Shenzhen, China, in late 2011, will slot in at No. 8 on this list at 1,449 feet once it opens.
When it was constructed in 1931, the Empire State Building was the tallest building in the World. Today, it's ranks 19th at 1,250 feet tall and and 102 floors.