One World Trade Center, America's tallest building, has welcomed its first tenants, publishing group Conde Nast, in a symbolic moment 13 years after the 9/11 attacks that brought down the original Twin Towers.
About 175 executives of the group that publishes magazines like The New Yorker and Vanity Fair, filed through the doors of the building on Vesey Street, just steps from the memorial and museums erected at the site where the Twin Towers once stood.
The iconic Manhattan landmark collapsed in fire and smoke on September 11, 2001 after being hit by hijacked airliners flown by Al-Qaeda militants. Nearly 3000 people were killed in the attacks, which also targeted the Pentagon.
The new tower is the centerpiece of a five tower complex. It stands 104 stories and 1,776 feet (540 meters) tall, a height representing the year the United States declared its independence from Britain.
"Some people are nervous, some people are just excited to move downtown and start a transformation for the company, to help revitalize lower Manhattan," said John Duffy, director of policies and controls at Conde Nast.
Duffy, who worked in the old World Trade Center in the 1980s, acknowledged that "some people are gonna be nervous, feeling they could be potential targets again."
But he said authorities have worked hard to make a new building that is "probably indestructible."
Conde Nast is expected to have a total of 3,400 employees in January spread across floors 20 to 44 of the building.
One World Trade Center, designed by architect David Childs, has become a Big Apple landmark of its own, with simple lines, a needle-like spire and mirrored windows that shimmer brightly in the sunlight.
Operated by the Durst Organization, the building is owned by the Port Authority of New York and New Jersey, a governmental agency.
Its other tenants include the China Center New York, Legends Hospital Group and the General Services Administration, which supports the basic functions of federal agencies.
Durst Organization spokesman Jordan Barowitz told AFP that 60 percent of the office space is already rented.
- 'Great day for New York' -
For Vanity Fair publisher Chris Mitchell, the site's reopening marked "a great day for New York and a great day for Conde Nast, an amazing experience for the company."
He spoke to reporters at a corner of the tower, with police keeping close watch on the area.
The public will be able to access an observation deck on floors 100 to 102, which is to open in the spring.
The new WTC complex includes five towers, a memorial and museum that opened in May, a center for the performing arts and about 55,000 square feet (5,100 square meters) of retail space that connect to an extensive transportation network.
Calling itself a "shining beacon for New York's downtown," the One World Trade Center has a sustainable design at its core that integrates renewable energy, interior daylighting, the reuse of rainwater and recycled construction materials.
As for safety, the building features dense fireproofing, biochemical filters, extra-wide pressurized stairs, multiple backup emergency lighting, and concrete protection for all sprinklers.
"Exits are designed to ensure easy evacuation, and all safety systems are encased in the core wall, with the enhanced elevators," according to the site's property managers.
The first new building erected at the site of the attacks was the Four World Trade designed by Japanese architect Fumihiko Maki. It opened in November 2013.