New York's One World Trade Center, seen from the 68th floor of the Four World Trade Center, will officially become the tallest building in the United States when completed next year, the Council on Tall Buildings and Urban Habitat has announced. Standing 541 meters on the site of the former World Trade Center and with 104 floors, it will move ahead of Chicago's 442-meter Willis Tower. SHANNON STAPLETON/ REUTERS

The first office tower at Ground Zero since the Sept 11, 2001, attacks that destroyed the World Trade Center opened on Wednesday, marking a comeback for the Lower Manhattan site.

Sheathed in glass, 4 World Trade Center is the smallest of the four main towers on the site where 2,700 people died when hijacked airplanes crashed into the towers. It stands 298 meters tall, a shorter, simpler version of One World Trade Center, which will not be completed until early 2014.

"This isn't just a building. It's a symbol of our rebirth. It speaks to our promise to never forget," said Manhattan Borough President Scott Stringer at a ribbon-cutting ceremony attended by officials, friends, construction workers on the site and tourists snapping pictures.

Mayor Michael Bloomberg and Japanese architect Fumihiko Maki took part in the opening ceremony in Lower Manhattan.

Maki said he designed the building to have a "strong sculptural effect but with a quiet presence" and an "ambience of calm and dignity".

The 72-story building stands empty at the moment, although two government agencies have signed leases for half of the building's space. Both the Port Authority of New York and New Jersey, which owns the site, and the city of New York committed to the space years ago to help jumpstart rebuilding efforts.

Since the attacks, disagreements among New York City, the state, the federal government, developers, insurers, victims' families and others have slowed construction. Developer Larry Silverstein, who held the lease to the site when it was attacked in 2001, has played a key role in shaping the project's design, security and cost.

"The world is recognizing that we've moved from 12 years of controversy and construction to having a real place that is coming back to life as a part of New York City," said Janno Lieber, who oversees planning, design and rebuilding for Silverstein Properties.

Silverstein spokesman Dara McQuillan said the developer was not troubled that the 213,677-square-meter building is only half leased.

In 2006, Silverstein opened 7 World Trade Center, just north of Ground Zero, and the company was the only tenant in the building. But by 2011, it was fully leased with such tenants as Moody's Corp and Mansueto Ventures, which publishes Fast Company and Inc magazines.

"We learned at 7 World Trade Center that when you build state-of-the-art, green, high-tech office buildings, they lease quickly," McQuillan said.

Reuters - AFP