The new Navy assault ship 'USS New York', built with World Trade Centre steel, passes lower Manhattan as it arrives in New York. Photo / AP

The new Navy assault ship 'USS New York', built with World Trade Centre steel, passes lower Manhattan as it arrives in New York. Photo / AP

NEW YORK — The new Navy assault ship 'USS New York', built with World Trade Centre steel, arrived in its namesake city Monday with a 21-gun salute near the site of the 2001 terrorist attack.

First responders, families of 11 September victims and the public gathered Monday at a waterfront viewing area where they could see the crew standing at attention along the deck of the battleship gray vessel.

The big ship paused.

Then the shots were fired, with a cracking sound, in three bursts.

The bow of the $1 billion (NZ$1.39 billion) ship, built in Louisiana, contains about 7.5 tonnes of steel from the fallen towers.

"It's a transformation ... from something really twisted and ugly," said Rosaleen Tallon, who lost her fire-fighter brother, Sean in the 2001 terrorist attacks.

"I'm proud that our military is using that steel."

Tallon said her brother who was a Marine, would have also been proud.

Jo-Ann Atlas, who lost her husband, fire Lt. Gregg Atlas, draped a flag-themed banner along the fence.

The names of emergency workers who died were written on the red stripes.

"We have to remember. It's a way to honour them," she said.

Members of the public included Nancy DiGiacomo, who came with her husband, 9-year-old son, mother and sister.

"I just thought it was important to see the transformation of the tragedy's wreckage," said DiGiacomo.

"From that, something else can come of it."

Lt. Cmdr. Colette Murphy, a Navy spokeswoman, said she was excited for those serving on board to see the city's "awe-inspiring" welcome.

At a short ceremony later at Pier 88 near the site of the aircraft carrier, the USS Intrepid, Mayor Michael Bloomberg said the USS New York couldn't have a more fitting name, representing freedom, courage and resilience.

"This ship is actually a physical representation of that spirit with steel from the World Trade Centre built into its bow so every friend that sets foot on it and every foe that dares challenge it will feel its power and know that it is literally made from the heart and soul of the city that has sacrificed so much," the mayor said.