In 1967, Joe Alba was a 26-year-old ironworker laying steel beams at the World Trade Center.

Thirty-five years later, he watched the last steel column of the demolished trade center being removed in the first of a series of ceremonies marking the end of the recovery effort.

``I was too young to understand how important this building was,'' he said. ``I never believed it would go down.'' 

 Alba, 60, was one of hundreds of construction workers honored Tuesday for their work at the site since the terrorist attacks on Sept. 11.

With chants of ``USA! USA!'' in the background, the steel column was severed with a torch and placed on a flatbed truck, where construction workers draped the beam with an American flag and laid a wreath of red, white and blue flowers on top. Some wrote messages on the column; others touched it as if it were a coffin.

Hundreds of U.S. sailors in town for Fleet Week and dozens of New York firefighters and police officers lined a ramp leading out of the site. They saluted as the construction workers filed by, many with tears in their eyes.

``It means a lot to people — it's like a flag, which is a piece of cloth, but it represents our country and an idea. The idea of the beam is our strength, our resilience,'' said Richard Streeter, who has operated an excavator at the site since Sept. 12.

The 30-foot piece of steel survived when the twin towers collapsed into a mountain of 1.8 million tons of rubble. For months it was covered by debris, but as the pile shrank the column was revealed, still standing where it was planted when the south tower was built more than 30 years ago.

Lt. John Keenan, a firefighter with Ladder 10, which is located across the street from where the south tower once stood, said he was at the ceremony to pay tribute to the construction workers.

``We couldn't have done it without them,'' he said.

Many construction workers had bonded with the rescue workers and said it would be hard to leave the job they poured their hearts into.

``There's been an adrenaline push to be here,'' said Bill Harris, a 50-year-old construction worker from Pearl River, N.Y. ``It's going to be hard to disconnect.''

Tuesday's ceremony was the first of three — for construction workers, rescue workers and families — that make up a gradual farewell to the round-the-clock recovery operation.

``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,'' Mayor Michael Bloomberg said.

On Thursday, the column will be removed from the site in a procession past an honor guard during the city's formal ceremony to mark the end of the recovery effort. It will begin at 10:29 a.m., the time the north tower collapsed Sept. 11.

A fire department bell will ring the signal for a fallen firefighter, then a stretcher with a folded flag will be carried out of the site, honoring the victims whose remains have not been found.

Of the 2,823 people killed in the attack, the remains of just 1,092 have been identified. But nearly 20,000 body parts have been recovered, and the medical examiner expects to continue identification work for at least eight more months.