One World Trade Center becomes tallest building New York City

One World Trade Center, the unfinished skyscraper where the Twin Towers once stood, became the tallest building in New York City on Monday.

Still under construction more than a decade after the Sept. 11 attacks, the building's skeleton surpassed the Empire State Building's 1,250-foot-high observation deck, reaching 1,271 feet  with the addition of a few steel columns.

Once known as the Freedom Tower, One World Trade Center will eventually measure 1,776 feet, including a 408-foot-tall needle that will be attached to the roof.

"The latest progress at the World Trade Center is a testament to New Yorkers' strength and resolve -- and to our belief in a city that is always reaching upward," New York City Mayor Michael Bloomberg said in a statement.

"This building has been a labor of love for many, and I congratulate the men and women who have worked together to solve the challenges presented by this incredibly complex project," he added.