Construction workers have hoisted the final spire piece to the top of the 1,776 feet tall One World Trade Center in New York's financial district.
The spire itself weighs around 758 tons and when installed will make the skyscraper the tallest structure in the Western Hemisphere and the third-tallest in the world.
Originally plans were to raise the two remaining spire pieces on Monday, but work was postponed because of winds. The top sections of the building were raised on Thursday - coincidentally on the second anniversary of the death of Osama bin Laden.
One World Trade Center became New York's tallest building a year ago standing at 1,271 feet above street-level. The building then was 21 feet higher than the Empire State Building's observation deck.