Two 25-ton steel columns one bearing the signatures of the American steelworkers who completed it rose at New York's ground zero on Tuesday, the first beams of the skyscraper that will replace the twin towers of the World Trade Center.

As construction workers, politicians and architects applauded, a massive crane lifted into place the first 31-foot-high column, which was painted with an American flag and the words "Freedom Tower."

A second column set a few feet away carried the signatures of steelworkers and politicians from Virginia, where it was worked on at a steel company before being shipped to New York.

A third column lay on its side, plastered with signatures of New Yorkers and September 11 victims' relatives as well as pictures of some firefighters killed in the 2001 attack. It will be installed in the next few days.

By next spring, 27 of the jumbo steel columns, which will one day anchor the skyscraper, are expected to rise to street level about 20 metres above the bottom of ground zero.

"Today the steel rises, the Freedom Tower rises from the ashes of September 11, and the people of New York and the people of America can be proud," Governor George Pataki said.

"America's strength is evident in these columns of steel the footings for the great monument to freedom that is rising on this hallowed site."

The 541-metre tower, set to open in 2011, is to be the tallest of the five skyscrapers planned for the site.

Lengthy negotiations over who would build the tower and security concerns have delayed the project.

The tower has had more than one design and groundbreaking; politicians laid a granite cornerstone in July 2004 to begin construction, but had to move the building after city police said it was too close to traffic, making it vulnerable to terrorism.

Construction began again this spring, after the site's owner renegotiated its lease with a private developer and took over construction.

Governor-elect Eliot Spitzer, who takes office next month, has said he planned to look again at designs for the tower. Federal and state agencies, including the governor's office, have agreed to occupy half of the building's office space.

There are also continuing worries over the amount of remains that may still lie beneath the site. Some 1,148 of the 2,749 victims of the Twin Towers attack are yet to be recovered or identified.

Plans for a memorial at the Freedom Tower have also raised objections from some victims' families. On Monday several family groups rejected New York City's plan for listing the names of victims from one tower in groups and with their affiliations, but then listing the victims of the other tower without such information included.

Source: China Daily