1 World Trade Center reaches 100 floors

One World Trade Center, left, now up to the 100th floor, and Four World Trade Center, right, overlook the ongoing construction of the site, Sunday, April 1, 2012 in New York. The unfinished One World Trade Center is one of the city's tallest structures. If construction continues at its current pace, it will pass the Empire State Building this spring. Four WTC will top out at 72 floors.