A 408-foot silver spire was installed on top of One World Trade Center in downtown Manhattan on Friday, bringing its official height to 1,776 feet and making it the tallest building in the Western Hemisphere. Since the tower was first announced, a debate has raged over whether or not it truly is the tallest. According to the Council on Tall Buildings and Urban Habitat — the authority on such matters — because the WTC’s spire is ornamental and not functional, it was counted in the building’s official height, edging out Chicago’s Willis Tower.