The quiet spread from New York to other observances across the nation and around the world.
Gov. George Pataki followed with a reading of President Abraham Lincoln's 1863 Gettysburg Address after the American Civil War. Then Rudolph Giuliani, the former mayor who guided the city after Sept. 11 last year, began a reading of the names of the 2,801 people who lost their lives where the Trade Center once stood.
The lower Manhattan ceremony was the first of three at the sites of last year's attacks. Ceremonies also took place at the Pentagon, where 189 people lost their lives, and at a field in Pennsylvania, where 40 passengers and crew died in the crash of United Airlines Flight 93.
At the Pentagon, in Arlington, Virginia, U.S. President George W. Bush marked the first anniversary of the Sept. 11 attack.
"The memories of a great tragedy linger here, and for all who knew loss here, life is not the same. ... The murder of innocents cannot be explained, only endured. And though they died in tragedy, they did not die in vain," Bush said at the ceremony.