and dark, alternately threatening and delivering rain. The ceremony took place not at ground zero, where construction cranes now rise like tentative fingers of hope, but near its southeastern corner, in Zuccotti Park. Ceremonies were also planned this morning at the Pentagon and in Shanksville, Pa., where the other two hijacked planes crashed that morning.

The families began trickling in at 7 a.m., some clutching bouquets of flowers, others holding heart-shaped balloons, eventually filling the park by the hundreds and taking refuge from sporadic drizzle under a sea of dark umbrellas.

And then, as it has for five years before, the remembrance ceremony assumed its recognizable form. At 8:40 a.m., the Brooklyn Youth Chorus took the stage, and sang the "Star Spangled Banner," their voices sounding like angels as mourners held aloft photos of people who, to them, are angels now, too. Afterward, the drummer for the New York Police Department marching band sounded a mournful heartbeat, and then the bagpipers began.

At 8:46 a.m., the moment the first plane struck the North Tower, a bell was sounded, as it has for six years now, and the gathered masses bowed their heads.

"On that day, we felt isolated, but not for long, and not from each other. New Yorkers rushed to the site, not knowing which place was safe or if there was more danger ahead," Mayor Michael R. Bloomberg said. "They weren't sure of anything except that they had to be here. Six years have passed, and our place is still by your side."And then 236 emergency workers from an array of city agencies and religious entities, began reading, in alphabetical order, the names of that day's 2,750 victims in Lower Manhattan.

At 10 a.m. after a moment of silence to mark the collapse of the South Tower, Rudolph W. Giuliani made a brief statement. The presence of the former mayor, who is running for president, had stirred controversy, although he has attended every year.

"On this day six years ago and on the days that followed in the midst of our great grief and turmoil, we also witnessed uncompromising strength and resilience as a people," he said. "It was a day with no answers, but with an unending line of those who came forward to try to help one another.

Mr. Giuliani added: "Elie Wiesel wrote wrote this about the blackest night a human being can know: 'I have learned two lessons in my life. First, there are no significant literary, psychological or historical answers to human tragedy, only moral ones. Second, just as despair can come to one another only from other human beings, hope too can be given to one only by other human beings.'"

Construction at ground zero was stilled for the day, but the roar of an awakening Manhattan filled the air. Cars crept along West Street, sirens yelped, and workers in nearby office buildings peered down from windows at the proceedings, and then retreated back to work.

And huddled under their umbrellas, shifting awkward because there were no seats, the relatives held up the photos of their perished loved ones, visceral reminders of the day they may hate to remember but cannot bear to forget.

"All those amazing incredible people who became victims that day. Please know your loved ones along with your loved ones families and friends are remembered in our prayers," said one woman, after reading off the names of a dozen victims.

"Please know that we will never forget."