If wind speeds aren't prohibitive Monday, a steel column will be lifted on top of the existing framework of 1 World Trade Center, making it New York's new tallest building. The first column of the 100th floor of 1 World Trade Center will put the tower 21 feet higher than the Empire State Building – inching it all the closer to its final height. By the time the tower is complete next year, it will stand at 1,776 feet. Carol Willis, director of the Skyscraper Museum puts 1WTC's ascendancy over the Empire State Building into context. WNYC digital producer Stephen Nessen spent a lot of time on the site of 1WTC this summer. He explains what it took to make a structure this massive.