Silence fell on ground zero Wednesday morning, precisely a year from the moment when a terrorist-guided jetliner sliced through a crystal blue sky and murdered thousands.

Quiet spread across New York -- a city still in mourning a year after the obliteration of its tallest buildings, the World Trade Center -- to the South Lawn of the White House to other observances across the nation and around the world.

Gov. George Pataki followed with a reading of Lincoln's Gettysburg Address. And then Rudolph Giuliani, the former mayor who guided the city with quiet strength in the days after last Sept. 11, began a reading of the names of the 2,801 souls who lost their lives where the trade center once stood.

''Gordon M. Aamoth Jr.,'' he intoned. ''Edelmiro Abad. Maria Rose Abad. Andrew Anthony Abate …''

The time was 8:46 a.m. EDT, the instant when American Airlines Flight 11 crashed into the north tower of the gargantuan complex. As the mournful tones of classical music played in the background, family members of the dead picked up the list where Giuliani left off, and onlookers hugged and cried.

The lower Manhattan ceremony was the first of three tableaux at the sites of last year's attacks. Next would come ceremonies at the Pentagon, where 184 men and women died, and at a field in southwestern Pennsylvania, where 40 passengers and crewmembers lost their lives in the crash of United Airlines Flight 93.

But the day's memorials were hardly limited to those sad places. A cascade of memorial events around the globe marked a moment whose echoes still resound from New York to Afghanistan, and everywhere in between -- a moment that even a year later left many transfixed by the horror, burdened by sadness, plagued by fears.

''A day of tears,'' said President Bush, ''and a day of prayer, and a day of national resolve. It also needs to be a day in which we confirm the values which make us unique and great.''

It was a day, too, of jitters and heightened security. Officials issued a ''code orange'' alert and warned that terrorists who struck last Sept. 11 might strike again. The moment of the first attack was commemorated around the globe, starting in New Zealand, with the first line of the Requiem that Mozart wrote in his dying days.

''Requiem aeternam dona ets, Domine, et lux perpetua luceat ets,'' sang the Orlando Singers Chamber Choir at St. Luke's Presbyterian Church in Rumuera: ''Grant them eternal rest, O Lord, and may perpetual light shine on them.''

Choirs in 20 time zones around the world were to sing those words, each of them beginning at 8:46 a.m., local time.

In Australia, 3,000 people in red-white-and blue clothes assembled on a beach to make a human flag. In Paris, two powerful beams of light were projected into the sky.

A special Mass for firefighters was held at a Rome basilica, and Pope John Paul II dedicated his weekly audience to the attacks. ''No situation of hurt, no philosophy or religion can ever justify such a grave offense on human life and dignity, '' he said.

In the days after the towers fell, New Yorkers grew accustomed to the wail of bagpipes at hundreds of funerals for firefighters and police. Early Wednesday, bagpipers and drummers assembled for a relay -- from the five boroughs, two at a time, to ground zero.

But while the focus is on the places that suffered the most, ceremonies marking Sept. 11 -- prayer, the tolling of bells, candlelight vigils, releases of doves and balloons, riderless horses, flags at half-staff, moments of silence and others of music -- were everywhere.

There were homier demonstrations, as well. In Montgomery, Ala., at E.D. Nixon Elementary School, sixth graders and their teachers baked cookies to bring to their local firefighters. It was their idea, said principal Terese Goodson: ''They just wanted to do something.''

And yes, Goodson replied to their pleading, they could add a touch of red to their white-blue-and-khaki uniforms on Sept. 11.

Fifteen percent of American businesses planned to give their employees red-white-and-blue ribbons or pins for the day, according to a survey by the Society for Human Resource Management; about a third said they would observe a moment of silence on Wednesday. Just 4 percent said they would give their workers the day off with pay.

The stock exchanges delayed their openings until after 11 a.m. Telemarketers hung up their phones. Said Perry Young, head of a calling center in Omaha: ''If I received a call at home on that day from somebody trying to sell me something, I would be personally offended.'' As they did a year ago, television networks struck everything else from their schedules.

Some airlines -- still struggling to regain passenger traffic they lost a year ago -- scaled back their schedules, as travelers avoided the skies on this day.

A year ago, it is believed passengers and crew members on United Flight 93 fought desperately with the hijackers who had commandeered their plane. All 40 died, but the plane never reached its target -- the Capitol? the White House? -- and their heroism became legend.

On Tuesday, 500 of their friends and relatives went to the spot in Shanksville, Pa., where Flight 93 crashed. Clutching flowers and flags, they walked the field where the plane crashed.

But other survivors kept their distance from an anniversary of heartache.

Barbara Minervino of Middletown, N.J., planned to attend a private Mass along with others from that town, which lost dozens of its people at the World Trade Center. Louis Minervino was at his 98th floor office in Tower One when the first jet hit.

But she had no intention of going to lower Manhattan on Wednesday. She would do the laundry, go to the beach with her two daughters, make dinner -- her husband's favorite, lasagna. She wanted to honor his life, not his death.

''We are in our new normalcy,'' she said. ''It's not the normalcy we had before. We're without our loved ones. It certainly will never be the normalcy we had on Sept. 10.''

Jerry Schwartz/The Ironton Tribune