"It's a culmination of a tremendous amount of team work ... rebuilding the New York City skyline once again," said Estevez, a project manager for Tishman Construction. He said the workers around him were "utterly overjoyed."
Installation of the final two sections of the 408-foot, 758-ton spire was completed after pieces of it had been transported to the roof of the building last week. It will serve as a world-class broadcast antenna.
The building is at the northwest corner of the site where the twin World Trade Center towers were destroyed in the Sept. 11, 2001, terrorist attacks.
Lee Ielpi, whose firefighter son died after responding to the attacks, watched workers secure the spire from his office at the nearby 9/11 Tribute Center, which he co-founded.
"The building looks spectacular. ... I'm looking forward to the day when the cranes come down and they light the spire at night," he said. "It's supposed to be a very moving experience."
The Port Authority of New York and New Jersey, which owns the site, said the LED-powered light would be activated in the next few months.
"It's going to have a light that you can see from tens of miles away," said Port Authority Vice Chairman Scott Rechler. "And that light will change colors and in the next few months we are going to be activating that light, and it will be a beacon of hope just like the Statue of Liberty."
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.
If it didn't have the spire, One World Trade Center would be shorter than the Willis Tower in Chicago, which stands at 1,451 feet.