EarthCam

In a matter of days, One World Trade Center could be the tallest building in Manhattan and one of the tallest in the world.

The building is expected to be taller than New York's iconic Empire State Building, which currently rises 1,250 feet to the 102nd floor observation deck.

One World Trade is being built on the site of the original World Trade Center towers - or Twin Towers. They were the tallest buildings in the city, but were destroyed in the Sept. 11 terror attacks, in which an estimated 3,000 people were killed.

The progression of construction on One World Trade can be seen in a two-minute, time-lapse video from EarthCam, the international webcam technology company.

Construction is estimated to be finished in 2013 or 2014. One World Trade Center will stand 1,776 feet tall.

The construction began six years ago. One hundred floors have been built so far, and four more remain before the tower is completed.

The site also is home to 4 World Trade Center and the 9/11 Memorial Plaza.