♪ we built this city on rock 'n' roll ♪ ♪ we built this city on rock 'n' roll ♪ ♪ we built this city we built this city on rock 'n' roll ♪ ♪ built this city nice shot that. you got to love that. it is official, new york city has a new tallest building and, of course, it does mark an emotional milestone more than a decade after 9/11. >> yes, the building reaching new heights symbolizing the spirit and rebirth of manhattan's skyline. abc's bob woodruff shows us how we got to this incredible moment. >> reporter: with this one beam, the world trade center reclaimed the skyline. new york's tallest building, 1,250 feet high, so high not even 8 statues of liberty would reach the top. >> really a symbol of the