6. One World Trade Center, U.S.A.
The first U.S. building on the list, and the tallest skyscraper in the Western Hemisphere. A phoenix rising from the ashes of the greatest tragedy in all skyscraper history: the September 11th attacks, which saw the destruction of the original World Trade Center buildings, themselves, once the tallest structures in the world.
Clearly, this tower needed to be more than just a skyscraper; it had to stand as a defiance of terrorism and a memorial of tragedy. David Childs of Skidmore, Owings & Merrill took up the challenge, with construction beginning on April 27th, 2006.
Building continued for the next seven years, with the tower topping out at 541 metres, or 1,776 feet: a deliberate reference to the year of the signing of the United States Declaration of Independence. And while the official name for the building might be One World Trade Center, it will likely always be known by the more colloquial name, the name it was given before it had even been built, Freedom Tower.