Workers installed the final sections of the silver spire atop the One World Trade Center (WTC) Friday, which brings the iconic New York City structure to a height of 1,776 feet (541 metres).
The building has been built in the northwest corner of the site where the twin towers were destroyed in 9/11 terror attack.
The 408-foot (124-metre) spire will serve as a world-class broadcast antenna. An LED-powered light emanating from it will be seen from far away, Xinhua reported.
The building was already the tallest in New York City. With the addition of the spire, it becomes the tallest building in the Western hemisphere and the third tallest in the world.