DALLAS » The nation solemnly marked the 50th anniversary of President John F. Kennedy’s assassination today with subdued remembrances at Kennedy’s grave and the infamous site in downtown Dallas where the young, glamorous president was gunned down in an open-top limousine.

Flags flew at half-staff, and moments of silence were planned for the hour when Kennedy was shot riding in a motorcade. The quiet reverence extended across the Atlantic Ocean to his ancestral home in Ireland.

Shortly after sunrise, Attorney General Eric Holder paid his respects at Kennedy’s recently refurbished grave at Arlington National Cemetery, where a British cavalry officer stood guard, bagpipes played and a flame burned steadily as it has for the last half-century.

About an hour later, Jean Kennedy Smith, 85, the last surviving Kennedy sibling, laid a wreath at her brother’s grave, joined by about 10 members of the Kennedy family. They clasped hands for a short, silent prayer and left roses as a few hundred onlookers watched.

Dallas was bitterly cold, damp and windy, far different from the bright sunshine that filled the day Kennedy died.

About 5,000 tickets were issued for the free ceremony in Dealey Plaza, which is flanked by the Texas School Book Depository building where sniper Lee Harvey Oswald perched on the sixth floor.

A stage for the memorial ceremony, just south of the depository building, was backed with a large banner showing Kennedy’s profile. Video screens showed images of Kennedy with his family.

People began assembling for the event hours ahead of time.

"President Kennedy has always been kind of revered in our family," Colleen Bonner, 41, of suburban Hurst, said. "I just wanted to honor his memory, and I wanted to be a part of history."

The U.S. Naval Academy Men’s Glee Club was to perform at the ceremony in a nod to Kennedy’s military service, and an Air Force flyover was planned. A moment of silence was set for 12:30 p.m., when the president was shot.

Numerous events were held around Dallas this year to mark the anniversary, including panels of speakers who were there that day, special concerts and museum exhibits.

In Boston, Gov. Deval Patrick and Maj. Gen. Scott Rice of the Massachusetts National Guard endured a heavy rain during a wreath-laying ceremony at the Kennedy statue on the front lawn of the Statehouse. The statue, dedicated in 1990, has been largely off-limits to public viewing since security procedures put in place after the 9/11 terrorist attacks. But the area was opened to visitors today.

Both of Kennedy’s grandfathers served in the Massachusetts Legislature and in January 1961 the president-elect came to the Statehouse to deliver one of his most famous addresses, which came to be known as the "City on a Hill" speech, just before leaving for his inauguration in Washington.

Earlier Thursday, in Dublin, a half-dozen Irish soldiers toting guns with brilliantly polished bayonets formed a guard of honor outside the U.S. Embassy as the American flag was lowered to half-staff. An Irish army commander at the embassy drew a sword and held it aloft as a lone trumpeter played "The Last Post," the traditional British salute to war dead. A bagpiper played laments including "Amazing Grace." A U.S. Marine raised the flag again as the bugler sounded an upbeat "Reveille."

More than a dozen retired Irish army officers who, as teenage cadets, had formed an honor guard at Kennedy’s graveside gathered in the front garden of the embassy in the heart of the Irish capital to remember the first Irish-American to become leader of the free world.

Together with Irish Foreign Minister Eamon Gilmore and embassy staff, they observed a minute’s silence and laid two wreaths from the Irish and American governments in memory of JFK.

The former cadets invited by Jacqueline Kennedy to serve as the graveside honor guard described the awe — and fear — they experienced as they traveled to the United States 50 years earlier.

"We were young guys, all pretty much 18. We had no passports, no visas. None of us had flown before," said retired Col. Brian O’Reilly, 68. "We were told on the Saturday night we were wanted for the funeral. The next day, we were on the plane with our own president (Eamon de Valera) heading for Washington."

The day of the funeral was crisp and windless, with trees full of autumn leaves and a cloudless blue sky, the sun blindingly low on the horizon.

Associated Press writers Bob Salsberg in Boston, Matthew Barakat in Washington and Shawn Pogatchnik in Dublin contributed to this report.