It's been an exciting week for the city's various World Trade Centers: 1 WTC is officially the tallest building in the nation (John Stewart confirmed it, among other things), and down the street, 4 WTC has officially opened its doors for businesstumbleweeds.

Construction on the 72 floor, 978-foot-tall building commenced in August of 2009, and finished up earlier this month. Special construction cameras captured the whole thing, documenting the building's progress in 250,000 megapixel images for a "complete historic record of the construction process," according to EarthCam, the company behind the project.

So far, the building's only tenants are the Port Authority and the City of New York's Human Resources Administration, meaning that at least for now, nearly half of it is vacant. But Mayor Bloomberg, who took office when the site was still smoldering ash following 9/11, waxed nostalgic about the skyscraper's completion.

“The opening of 4 World Trade Center is a big step forward in our journey back from 9/11,” he said. “The men and women who built it — and who are building 1 World Trade and the other buildings — understand that this is more than just a construction project. They are helping the city to heal, and they’re helping to right a terrible wrong.”