"We are opening a bright new chapter," Bloomberg said at the Ground Zero construction site, surrounded by other officials. "This is a great day for New York."
While the newly opened Building Four is not be as tall as the still-incomplete neighbouring One World Trade Center, which was officially deemed the tallest building in the US Tuesday, the
72-story building is well visible on the New York skyline with its 298 meters.
Construction on the building began in 2008.
One third of the more 200,000 square meters of office space in the building will be used as the new headquarters of the Port Authority of New York and New Jersey, the city's transportation agency, which owns much of the World Trade Center site.