To accomplish this, it uses the longest antenna ever deployed in space, longer than the height of the Empire State Building.

BBC: Atmosphere Nasa

Friday's final installation, raising the building's height to 1, 776 feet, makes One World Trade Center the tallest skyscraper in the U.S. and third-tallest in the world, although building experts dispute whether the spire is actually an antenna a crucial distinction in measuring the building's height.

WSJ: Spire permanently installed on WTC tower

The addition of the spire, and its raising of the building's height to 1, 776 feet, makes One World Trade Center the tallest structure in the U.S. and third-tallest in the world, although building experts dispute whether the spire is actually an antenna a crucial distinction in measuring the building's height.

WSJ: Spire permanently installed on WTC tower