With the addition of a single steel beam on top --- One World Trade Center in New York became the tallest structure in the city, surpassing the iconic Empire State Building. Construction teams placed the beam into position on its highest floor shortly after noon. Scott Rechler, Port Authority Vice Chairman. 　　Scott Rechler: "It's a very exciting day. One World Trade Center is much more than an iconic symbol for New York, New Jersey and our region. It is a symbol of liberty and pride for our entire country." 　　 The structure is built on top of Ground Zero --- the site of the fallen World Trade Center Towers When construction is completed next year, it will measure 1, 776 feet from the ground to the tip of its antenna. This will make it the third tallest building in the world. (Deborah Gembara/ Reuters)