Some stood amid headstones, fighting off chilly winds. Others gathered in chapels, in town squares and at marble halls. They were family members, friends and strangers, and they sought Friday to honor the sacrifices of the nation’s service members on Veterans Day.

Among the most poignant and notable of ceremonies occurred at Arlington National Cemetery, where mourners left ornaments and trinkets by headstones and where hundreds of people — including President Obama — came to pay their respects.

The president placed a wreath at the Tomb of the Unknowns and later held his hand over his heart as taps were played.

At the Vietnam Veterans Memorial, thousands assembled and many gave generously toward a planned multimillion-dollar learning center for the site. In Arlington County, residents rang a vintage Pennsylvania church bell. Students and professors at the University of Maryland convened in Memorial Chapel to honor their veteran colleagues.

And in Silver Spring, Rep. Chris Van Hollen (D-Md.) and Montgomery County officials celebrated the completion of Veterans Plaza, a milestone in the decades-long process to redevelop the city’s downtown and remember those who served.

Friday was a particularly significant Veterans Day not only for its date — 11/11/11 — but also for events that transpired since the last one. The death of Osama bin Laden. Allegations that the nation’s largest military mortuary mishandled troops’ remains. The 10th anniversary of 9/11. The announcement that the Iraq war will imminently end.

First lady Michelle Obama, Defense Secretary Leon E. Panetta and D.C. Mayor Vincent C. Gray were among those who visited Arlington. The president told the crowd that he had ordered the hiring of more veterans by the federal government and called for a “new spirit of sacrifice.” He referenced the coming end of the Iraq war, which drew cheers.

“After a decade of war, the nation we now need to rebuild is our own,” Obama said before heading to San Diego to attend a college basketball game aboard an aircraft carrier.

Two miles away, federal officials and veterans urged families to remember a different war. The ceremony by the Vietnam Veterans Memorial was broadcast as part of a 12-hour telethon to raise funds for an education center planned for the memorial site. Event organizers said they garnered at least $2 million.

Joe Galloway, who served as a journalist for United Press International during the war, told the audience that the center would help civilians, especially politicians, better understand battle.

“We need smarter, better-educated politicians,” he said. “They should not be allowed to vote for a war if they don’t know what one is firsthand.”

John Dobish, who served in the Navy, said he was struck by Galloway’s criticism. “The politicians in Washington aren’t accomplishing anything by keeping us in Iraq,” he said.

Meanwhile, Montgomery officials unveiled Veterans Plaza’s finishing touch: a three-piece memorial made of bronze and glass.

Van Hollen spoke briefly at the ceremony, apologizing for having lost his voice. He said he had been using it a lot over the past few days, “trying to talk some sense on that joint committee you may have heard about,” referring to the debt “supercommittee” on Capitol Hill.

Veterans representing each section of the military, many in uniform, showed up at the ceremony. Among them was Jack Hewitt, who was instrumental in the planning of the plaza.

Hewitt, one of seven brothers who fought in the Vietnam and Korean wars, said he is proud of being a veteran and of the county finishing Veterans Plaza.

“To be here as the county provides this [to remember] all the veterans in the county, state and country, I can do no more than to say thank you, thank you, thank you,” he said.