Thirteen years after two hijacked passenger aircraft brought down the twin towers that soared over the New York skyline, the World Trade Center once again opens for business.
The 104-story building's opening marks an emotional milestone for the United States.
The One World Trade Center is designed to be the safest commercial structure in the world and the premier commercial business address in New York.
On Monday, publishing giant Conde Nast started operations from its new global headquarters at the 22nd floor of western hemisphere’s new tallest building.
Conde Nast occupies nearly 1.2 million square feet to house its headquarters, along with the Vantone China Center, which has leased 190,000 square feet.
The US General Services Administration will lease more than 270,000 square feet of space under a 20-year agreement.
Currently, the One World Trade Center is more than 60 per cent leased, with another 80,000 square feet going to the advertising firm such as Kids Creative, stadium operator Legends Hospitality, investment adviser BMB Group and Servcorp.
Floors 100 to 102 will house an observation deck.
The observation deck, called the One World Observatory, will take visitors on an inspirational journey about the history of this iconic structure. The spectacular sight-seeing venue is projected to draw an estimated 3.8 million annual visitors to the top of the third tallest structure in the world.
The deck is approximately 1,250 feet above street level.
The One World Trade Center will also serve over 200,000 daily commuters and millions of annual visitors from around the world.
Over 11,000 tons of specially-designed structural steel was used to fully construct the WTC Transportation Hub, which is equivalent to the mass of 880 average sized school buses. Design of the Hub includes fully integrated, climate-controlled concourses, mezzanines and platforms featuring high performance lighting and elegant finishes.
The World Trade Center retail complex will be a centerpiece for the entire Lower Manhattan area, a district that is experiencing rapid growth in office occupancy, residential population, commuter traffic and tourism.
Rebuilding the devastated site has been an agonisingly slow and achingly expensive undertaking.
The opening date of the new World Trade Center was originally set at 2006. Then it changed to 2011, then 2012.
The cost of the steel and glass building, initially dubbed the Freedom Tower, has nearly doubled since it first emerged on drawing boards.