Americans gathered Tuesday to mark the sixth year since the Sept. 11 terrorist attacks, bowing their heads in respect as the names of thousands of dead victims were read out loud.
For the first time, a memorial ceremony was not held at the former site of the World Trade Center site because of increased construction at Ground Zero.
After relentless protesting by family members, the city agreed to let them lay flowers at a spot below street level near where the fallen Twin Towers once stood. The main part of the ceremony will be held in a park adjacent to the site where a list of victims will be read as has been the tradition.
The anniversary is marked by other firsts.
This is also the first year that a name of a person who did not die at the Trade Center will be included. The city agreed to add a name of an attorney, Felicia Dunn-Jones, who died of lung disease five months after the attacks.
There are hundreds who have become sick as a result of breathing in the toxins that filled the air after the site imploded. Many of those are rescue workers who spent days at the site.
To mark their sacrifice, firefighters for the first time this year were given the honour of going up to the podium and reading a list of victims.
This year is also the first that the anniversary falls on a Tuesday, the same day of the week the attacks actually occurred.
Unlike six years ago when the sun was shining through clear skies, the backdrop at the memorial was bleary, wet and grey with heavy clouds.
"That day we felt isolated, but not for long and not from each other," said New York City Mayor Michael Bloomberg, at the start of the ceremony. "Six years have passed and our place is still by your side."
The day was marked by a political presence, such as presidential hopefuls Democratic Sen. Hillary Clinton and Republican candidate Rudy Giuliani, who was mayor of the city at the time of the attacks.
Giuliani said his attendance is the furthest thing from a strategic political move.
"I was there when it happened and I've been there every year since then," he told The Associated Press. "If I didn't then it would be extremely unusual. As a personal matter, I wouldn't be able to live with myself."
As they have done each year, the crowd will take four minutes of silence, two for the time each tower was hit by an airplane and two more for the time each tower collapsed.
Around the country other ceremonies were held, including near the site of the Pentagon and a Pennsylvania field where airplanes also crashed at the hands of terrorists.
Some of the memorial ceremonies have actually been scaled back. City officials in New York said that fewer people attend the memorials each year. But in New Jersey, people objected when a local television station said they would not air the four-hour ceremony live. Station officials reversed their decision.
Overseas, U.S. soldiers fighting in Afghanistan marked the day by watching in silence as the American flag on their base was lowered to half-staff.
The families of 24 Canadian victims who died during the World Trade Center attack gathered in Toronto. They also gathered to remember another terror attack that killed 392 people killed by a bomb aboard an Air India flight that took off from Canada in 1985.
"September 11, 2001 was truly a day that shook the world," said Canadian Prime Minister Stephen Harper speaking to Australia's Parliament days before the anniversary. "Six years on, the horrific images from that morning still evoke anger, sorrow and - as intended - terror.
"The buildings may have been American, but the targets were every one of us: every country and every person who chooses tolerance over hatred, pluralism over extremism, democracy over tyranny," he said.
A total of 2,974 people were killed by Sept. 11 terror attacks: 2,750 at the World Trade Center, 40 in Pennsylvania and 184 at the Pentagon. Those numbers do not include the 19 hijackers.
With files from The Associated Press
