03/11/2014 10:45 GMT | Updated 04/11/2014 05:59 GMT

1 World Trade Centre Opens For Business 13 Years After 9/11

NEW YORK -- More than 13 years after planes toppled the Twin Towers, the central building constructed as their replacement finally opened for business on Monday, with workers moving into 1 World Trade Centre.

Publisher Condé Nast, which includes titles such as Vanity Fair and Vogue, has moved 175 employees into the building, with the company occupying floors 20 to 44.

Ultimately, Condé Nast will move around 3,400 members of staff to the site in Lower Manhattan, migrating employees from their current Times Square headquarters to 1 World Trade Centre by early next year.

Condé Nast spokeswoman Patti Rockenwagner told the New York Post: “Condé Nast is proud to be a part of this important moment of renewal for the city of New York.”

The tower, which is the largest in the western hemisphere, stands 1776-feet tall - the height represents the year of United States independence - and boasts a observation deck on its 102 floor, though this won’t be open to tenants until mid next year.

The tower, which costs nearly $4 billion to construct and has 3.5 million square feet of space, was originally scheduled to open in 2006, however the project suffered serious delays over financing and design.

Around 60% of the building’s office space has currently been leased, with other tenants including the US Army Corps of Engineers and US Customs and Border Protection.

The Twin Towers were felled in 2001 by al Qaeda terrorists, who piloted two hijacked passenger jets into the buildings, an attack that killed 2,753 people.

1 world trade centre