Workers will erect steel columns that will make its unfinished skeleton a little more than 1,250 feet high, just enough to peak over the roof of the observation deck on the Empire State Building.
The milestone is a preliminary one. Workers are still adding floors to the so-called "Freedom Tower" and it isn't expected to reach its full height for at least another year, at which point it is likely to be declared the tallest building in the United States, and third tallest in the world.
Those bragging rights, though, will carry an asterisk.
The issue involves the 408-foot needle that will sit on the tower's roof. Count it, and the World Trade Center is back on top. Otherwise, it will have to settle for No. 2, after the Willis Tower in Chicago.
"Height is complicated," said Nathaniel Hollister, a spokesman for The Council on Tall Buildings and Urban Habitats of Chicago.
Experts and architects have long disagreed about where to stop measuring super-tall buildings outfitted with masts, spires and antennas that extend far above the roof.
Consider the case of the Empire State Building: Measured from the sidewalk to the tip of its needlelike antenna, the granddaddy of super-tall skyscrapers stands 1,454 feet high, well above the mark being surpassed by One World Trade Center.
Purists, though, say antennas shouldn't count when determining building height. An antenna, they say, is more like furniture than a piece of architecture. Like a chair sitting on a rooftop, an antenna can be attached or removed.
The Empire State Building didn't get its distinctive antenna until 1952.
Excluding the antenna brings the Empire State Building's total height to 1,250 feet. That was still high enough to make the skyscraper the world's tallest from 1931 until 1972.
From that height, the Empire State seems to tower over the second-tallest completed building in New York, the Bank of America Tower.
Yet, in many record books, the two skyscrapers are separated by just 50 feet.
That's because the tall, thin mast on top of the Bank of America building isn't an antenna, but a decorative spire.
Unlike antennas, record-keepers like spires, hearkening back to a time when the tallest buildings in many European cities were cathedrals. Groups like the Council on Tall Buildings, and Emporis, a building data provider in Germany, count spires when measuring the total height of a building.
Designs call for One World Trade Center's roof to stand at 1,368 feet -- the same height as the north tower of the original World Trade Center. The building's roof will be topped with a 408-foot, cable-stayed mast, making the total height of the structure a symbolic 1,776 feet.