As New York slept, the day began on the other side of the globe with a tree-planting ceremony in New Zealand, one of many held on the grounds of those United States embassies around the world that remained open despite the threat of a new attack.
At Australia's Surfers Paradise, a popular vacation resort, dozens of people led by firefighters and ambulance staff took to the beach to form a human stars and stripes flag.
"It's a sacred time," said Barry Brazel, of the Queensland Fire and Rescue Service, adding that the day holds a special meaning for firefighters of all nationalities.
In Tokyo, flowers were left in front of the U.S. embassy by Japanese wishing to express their sympathies, and a group of Buddhist monks gathered in the same place, to chant memorial prayers.
At London's St. Paul's Cathedral, 3,000 white rose petals fluttered down from the dome - one for each victim who died last Sept. 11.
Hundreds stood in front of St. Paul's Cathedral as relatives and friends of the dead and representatives of Britain's emergency services worshipped inside with Prime Minister Tony Blair and his wife Cherie, Prince Charles, Prince Harry and U.S. Ambassador William Farish.
The St. Paul's service was the centerpiece of Britain's remembrances, but people around the country held memorials of their own and observed a moment of silence to mark the start of last year's violent chain of events.
Religious leaders condemned the attacks.
"No situation of hurt, no philosophy or religion can ever justify such a grave offense on human life and dignity," Pope John Paul II said at his weekly audience at the Vatican. But he called on the world to heal injustices that cause explosive hatreds.
At London Central Mosque, Muslim leaders offered Quranic prayers for peace, justice and tolerance.
At a commemoration at United Nations headquarters in New York, Secretary-General Kofi Annan challenged the world Wednesday to defeat terrorism by "acting as one," calling for a renewal of the surge of global unity in the days after the Sept. 11 horrors one year ago.
Not all saw the day as a time to mourn.
In Iraq, the state-owned Al-Iktisadi newspaper covered its front page Wednesday with a photograph of a burning World Trade Center Tower and a two-word headline in red: "God's punishment."
"Events like Sept. 11 are sad but it is an opportunity for the American people to feel what bombing could do to nations," said Ali Ahmed, a 47-year-old who owns a Baghdad stationery shop.
But around the world, it was a day of simple, heartfelt gestures. In Sydney, Australia, thousands of motorists turned on their headlights at 8:46 a.m. as a mark of respect for those who died.
Ireland, which took last year's attacks on the World Trade Center almost as personally as America, observed a minute's silence on Wednesday and held services to commemorate the dead.
"We knew a lot of those killed on a personal basis, because of exchange trips between Dublin and New York," said Brian Murray, chairman of the National Fire Brigades' Committee, attending a memorial service in a Dublin cathedral.
Cities around the globe paused for moments of silence, while candles were lighted and flowers laid outside U.S. embassies from Copenhagen to Moscow to Manila.
In Paris, two powerful beams of light were projected into the sky Tuesday to honor the memory of the victims - a project that was to be repeated Wednesday night.
In Pisa, Italy, a white banner placed by the Leaning Tower read: "From the tower to the towers. Sept. 11, 2002. Memory, solidarity and peace."
Beginning with choirs in New Zealand and Japan, 180 singing groups in 20 time zones began a "Rolling Requiem," singing Mozart's masterpiece. The requiem rang out at the National Theater in Belgrade, Yugoslavia, and was played by the Israeli Chamber Orchestra in Tel Aviv.
Political leaders around the world expressed their sorrow and solidarity.
"France knows what it owes America," French President Jacques Chirac told a ceremony at the U.S. ambassador's residence in Paris. "The French people stand with all their hearts at the side of the American people."
Russian President Vladimir Putin phoned President Bush to express his condolences, telling him: "In Russia, they say that time cures, but we cannot forget. We must not forget."
U.S. Ambassador Alexander Vershbow on Wednesday praised Russia's contribution to the international fight against terrorism and said President Vladimir Putin's quick support for the United States after the Sept. 11 terrorist attacks likely came as a shock to those who planned the carnage.
In the Middle East, Palestinian and Israeli leaders condemned the attacks - but disagreed about their significance.
At a commemoration ceremony in Jerusalem, Israeli Prime Minister Ariel Sharon included Yasser Arafat's Palestinian Authority among sponsors of terrorism that "are all inseparable parts of the same axis of evil that threatens the peace and stability in every place in the world."
Palestinian Cabinet Minister Saeb Erekat accused Sharon of "kidnapping" Sept. 11 and using it as a pretext for cracking down on the Palestinians.
In Afghanistan, a country battered and transformed by the events of Sept. 11, soldiers and diplomats unveiled the site where a piece of the World Trade Center was buried under the flagpole at the U.S. Embassy, as a bugler played taps and the Stars and Stripes was lowered to half staff.
A steel-gray marble headstone marked the resting place of the remains brought from the ruined towers by a Marine from New York. Inscribed on it: "We serve because they cannot."
At the U.S. Navy Base at Guantanamo Bay, Cuba, Marines held their own small ceremony. At the prison camp nearby, it was just another day behind bars for the 598 men from 43 nations suspected of links to al Qaeda or the Taliban. The detainees have no calendars and were not being told it was Sept. 11.
Protesters gathered, too.
In Bangkok, about 70 people including Thai monks and children held a peaceful protest outside the U.S. Embassy against U.S. military operations in Afghanistan and a possible attack on Iraq.
In the Philippine capital, Manila, supporters and opponents of the U.S. global war on terror held separate rallies to express sympathy for victims of last year's terrorist attacks.