The new viewing platform crowning the One World Trade Center began welcoming its first visitors on Friday, marking a symbolic step in New York's efforts to rebuild following the September 11 attacks.

From the One World Observatory on the 100th level, members of the public will have views stretching some 80 kilometers (50 miles) over the Manhattan skyline. Through floor-to-ceiling windows they'll be able to see key landmarks like the Brooklyn Bridge, Times Square, Central Park, the Statue of Liberty, and the Empire State building - whose total height is about 100 meters smaller.

At almost 400 meters (1,300 feet) above sea level, the new Trade Center, also known as Freedom Tower, is the tallest building in the Western Hemisphere.

The structure was built on the site of the former World Trade Center complex that was reduced to ruins when two passenger jets hijacked by al Qaeda flew into the Twin Towers in 2001.

"It's a great moment, it really says that we have turned the corner once and for all, and those that sought to attack us, lost once again," New York Mayor Bill de Blasio told CBS television last week during an early visit to the viewing platform.

Visitors are whisked to the top in one of five lifts, known as 'skypods,' in a speedy 47 seconds. The elevators are made entirely of screens, treating guests to a timelapse view of the city over the past 500 years.

Another part of the viewing experience, an installation called "Voices," tells the stories of the engineers and construction workers who rebuilt the World Trade Center.

The site is expected to become one of Manhattan's top tourist attractions. More than 350,000 thousand tickets were sold before the deck's official opening, and officials predict it will attract 3 to 4 million people each year.

Admission is free for family members of those who died on September 11, 2001, as well as those who worked in the rescue and recovery.

nm/msh (AP, AFP, dpa)