The spire has been added to the top of the One World Trade Center in New York.
The skyscraper took eight years to build and is now 541m (1,776 feet) tall, the tallest building in the western world.
The building replaces the twin towers which were destroyed in a terrorist attack in 2001, nearly 3,000 people died when the towers collapsed.
Below the new tower is a memorial to victims of the attack.
When it is completed, the One World Trade Center will have observation decks, restaurants and lots of office space.
Watch speeded up video of the tower going up between 2004 and 2012.
Courtesy of EarthCam