The operation was the first of a series of special ceremonies marking the end of the recovery efforts, which have been going on since the twin towers collapsed in the 11 September attacks.

It's like a flag, it represents our country and an idea - the idea of the beam is our strength, our resilience

Richard Streeter Excavator operator

Hundreds of construction and rescue workers watched as the 10-metre girder - which had become a makeshift shrine to those killed in the attacks - was gently lowered to the ground to the sound of bagpipes.

Some workers wrote personal messages on the beam, while others touched it like a coffin as it was covered in the American flag and loaded on to a truck.

At a ceremony at 1029 local time (1439 GMT) on Thursday - the exact time that the second tower collapsed - the beam will be hauled from the site and put into storage for possible use in a future memorial.

'Enormous job'

New York mayor Michael Bloomberg paid tribute to those who had worked on the clean-up operation.

The ceremony was highly emotional

"The construction workers who have dedicated themselves to this effort are on the verge of completing an enormous job, and in many ways this is their night to reflect and remember," he said.

"I'm glad it's over," said 60-year-old iron worker Joseph Alba, who was a member of the first work crew erecting steel on the site in 1967 and the last crew to demolish it.

The girder was covered for months with debris from a 1.8m-tonne pile of rubble resulting from the towers' collapse.

But, as the pile shrank, the column from the south tower was revealed.

Some relatives of victims want only a memorial on the site

Over recent months, workers put a flag on its top and covered the sides with messages and photos of victims.

Richard Streeter, who has been operating an excavator at the site since 12 September, spoke of the beam's significance.

"It means a lot to people," he said. "It's like a flag... it represents our country and an idea. The idea of the beam is our strength, our resilience."

Identification

Work at the World Trade Center site is finishing three months ahead of the schedule originally set by city officials, and at a fraction of the cost.

It had been believed that as much as $7bn would have to be spent to clear the rubble, but it has turned out to be about $750m.

Latest figures put the number of people confirmed dead or missing after the attack at more than 2,800, of whom just over 1,000 have been identified.

But almost 20,000 body parts have been recovered, and medical experts expect to continue identification work for another eight months.