On Monday workers added the first column of the 100th floor, making the new building 1,271 feet high. This new height inches past the Empire State Building's claim of tallest city skyscraper.
This time lapse photography gives us a quick look at the effort from the beginning. The building is being built about a pace of about one floor per week.
When it's finished in 2014, One World Trade Center will stand a symbolic 1,776 feet high the number representing the year America declared its independence.
It will have three observation decks, and 90 floors of office space.
Twin reflecting pools sit where the towers once stood -- in the shadow of the new building.
The names of those who died in the terrorist attacks of 2001 and 1993 are written on bronze panels, framing the pools.