A look at events marking the 12th anniversary of the Sept. 11 attacks:
NEW YORK CITY
In a sadly familiar ceremony, friends and relatives of World Trade Center attack victims gathered at the National Sept. 11 Memorial plaza to call out the names of the dead and read messages to lost loved ones.
A bell chimed to mark the moments when four hijacked jets crashed into the twin towers, the Pentagon and a field in Pennsylvania, and again to mark the moments when the two skyscrapers collapsed.
Several politicians attended, including New Jersey Gov. Chris Christie and former New York Gov. George Pataki, but none gave an address.
The ceremony also recognized victims of the 1993 World Trade Center bombing.
President Barack Obama held a moment of silence at 8:46 a.m. on the White House's South Lawn to mark the first attack in New York. He was joined by wife Michelle Obama, Vice President Joe Biden and his wife, Jill Biden. A bugler played taps.
Then, the president traveled to the Pentagon Sept. 11 memorial in Arlington, Va., where victims' families, attack survivors and military officials laid a wreath and held a moment of silence at 9:37 a.m. to mark the moment that Flight 77 hit the building. Obama said, "Our hearts still ache for the futures snatched away, the lives that might have been."
More than 200 people gathered at the Flight 93 National Memorial to read the names of 40 passengers and crew killed when the airliner crashed into a field near the small town of Shanksville.
Recalling the passengers and crew who had fought the hijackers, U.S. Interior Secretary Sally Jewell told the assembled families and spectators, "We never know when we'll be called to lay down our lives for others."
A wreath-laying ceremony in the city's Public Garden was followed by a commemoration at the Statehouse, during which participants read the names of more than 200 attack victims with ties to Massachusetts.
During the ceremony, a civilian bravery award named after 9/11 flight attendant Madeline Amy Sweeney was given to Carlos Arredondo, a Boston Marathon spectator who assisted a man who lost both legs in the April 15 bombing.
British princes William and Harry participated in a charity event organized by Cantor Fitzgerald, the brokerage firm that lost 658 employees in the World Trade Center collapse. The company and its affiliate BGC Partners are donating all of their Sept. 11 revenue to charity.
The princes, along with celebrities including Rod Stewart and actor Idris Elba, spent an hour working the phones on BGC's London trading floor. The U.S. version of the event featured Julianne Moore, Billy Crystal and Brooklyn Nets coach Jason Kidd.
A monument made from a piece of World Trade Center steel was unveiled in the town of Appleton to mark the area's role in helping stranded air passengers following the attacks. Residents in the region took travelers from around the world into their homes when American air space was closed after the 9/11 hijackings. More than 6,500 passengers and crew were diverted to nearby Gander, Newfoundland.
Some 300 U.S. and other coalition troops in Afghanistan gathered at noon for a memorial ceremony at Bagram Airfield to remember those lost on Sept. 11, 2001. The service was held near a nine-foot beam that is from the World Trade Center site and which many of the troops here pass on their way to their duties. Attendees saluted as a band played "The Star-Spangled Banner." The speeches focused on the sacrifices of troops in the years since the attacks, but also touched on some of the progress made in rebuilding Afghanistan.
About 200 military veterans observed the anniversary by fixing up the grounds of Texas Fire Museum, in one of many volunteer events around the nation recognizing Sept. 11 as a national day of public service.
The group MyGoodDeed, which organizes many of the service events, said it now gets about 50,000 pledges a year from people who plan to volunteer for a charitable activity on 9/11. Founders David Paine and Jay Winuk joined Alice Hoagland, the mother of Flight 93 victim Mark Bingham, in ringing the opening bell Wednesday at the New York Stock Exchange.
At a Navy graduation ceremony in northern Israel, President Shimon Peres paid tribute to 9/11 victims, saying the attack was among the worst terrorist crimes in history. "The mourning of the United States of America is also the mourning of Israel," he said.
The U.S. embassy in Israel held a ceremony in conjunction with the Jewish National Fund at the 9/11 Living Memorial in a Jerusalem forest. The memorial is among the largest commemorating 9/11 outside of the U.S.
Albania's prime minister-elect, Edi Rama, began an important policy address to that country's parliament by remembering the 9/11 attacks. "Sept. 11 dead are our dead too," he said, adding, "Even the Aug. 21 dead from the chemical weapons in Syria are our dead."