Once again, the city will pause for four moments of silence to mark the attacks that killed thousands. Family members will lay flowers by the fallen twin towers, and the names of more than 2,700 victims will be read.

But much will be different on the sixth anniversary of September 11, after tense arguments about where to hold the ceremony, if a presidential candidate should be allowed to speak, and whether focus on the commemoration has become excessive.

Firefighters, first responders and construction workers who helped rescue New Yorkers — and many who later recovered the bodies of the victims — were chosen this year to read the names of the dead in a small public park instead of the World Trade Center site. After bitterly objecting that they wanted to pay their respects closest to where their loved ones died, family members will be allowed to descend to the site below street level and lay flowers near where the towers stood.

“It’s still like visiting a grave on the person’s anniversary of their death,” the sister of a firefighter, Sean Tallon, who died that day, Rosaleen Tallon, said.

While the list of 2,750 victims killed in New York is read, Osama bin Laden planned to appear in a new video and read the will of one of the hijackers whose plane flew into the north tower.

Politics has played little role in past ceremonies, when siblings, spouses, and children offered heartfelt messages to their lost loved ones. The city’s firefighters, however, could raise several issues — they are among thousands who say they suffer persistent respiratory problems after inhaling dust from the trade center’s collapse. Two firefighters died just last month in a blaze at a skyscraper that had not been torn down since it was damaged on September 11, 2001.