Though New York's One World Trade Center is already the tallest building in the city, it is set to be even taller and to become the tallest building in the Western Hemisphere.
The last pieces of its spire will be built so that the total height of the building is 1,776 feet.
In December, installation began on the 800-ton, 408-foot spire. The spire is going to serve as a broadcast antenna, bringing back many radio channels that were destroyed on September 11.
The building offers the best view of Manhattan, and will open officially in 2014.
While builders began installing the spire, the city's chief medical examiner was working in an alley nearby where there are still debris with human remains from 9/11.
The spire is a joint venture between the ADF Group Inc. and New York's DCM Erectors Inc.
Though the building will be high once the spire is up, it will not be the tallest in the world. Currently, the tallest building in the world is in Dubai, at 2,700 feet.