The final steel beam was raised at Four World Trade Center Monday. YNN's Roger Clark has more on an especially exciting day for those who helped in the construction.

NEW YORK CITY, N.Y. -- It rose from the ground, headed 977 feet up, the final steel beam for World Trade Center 4. A momentous occasion for Frank Hussey, construction superintendent on the project.

Hussey said, "Today signifies where we are at as a city, as a nation and, you know, everyone that's, you know, a part of this rebuilding here, you know, it's a big day from where we were to where we are today."

Tower 4 will be the first office building to open on the 16 acre World Trade Center Site, scheduled for the fall of 2013 with a lobby that will look out on the 9/11 Memorial. The Port Authority and the city will be the first tenants, occupying about half the building..

"It's 72 stories in height and almost 1,000 feet in height. It has a great active presence at the street level, five levels of retail, two below grade and three above grade, much livelier in some ways, much more New York than the old World Trade Center was," said Janno Lieber, WTC Properties President.

The building will be the smallest of the towers on the site, which include One World Trade Center, or the Freedom Tower. That building is already the city's tallest building. It's scheduled to open in 2014. But this day was all about Tower 4.

“In a little over a year, 4 World Trade Center will be the newest addition to our neighborhood. And when we open the doors, it will not just be for our tenants, but for all New Yorkers," said WTC Site Developer Larry Silverstein.

It was also an emotional day for workers who have been part of the project.

"We witness the coming down of the two twin towers and we also witness and participate in the putting up of the replacements and it's wonderful," safety inspector Authority Ugbenin said.

"To see something like this that my grandchildren can look back and say my grandfather worked there, very emotional," labor steward Jesus Rivera said.

As one worker said, this shows the world that the city can come back and be even better than it was before the attacks.