President Bush said Thursday that after the terror attacks of Sept. 11, 2001 fade from memory, history will look back at America's response and conclude that "we did not tire, we did not falter and we did not fail."

Bush marked the seventh anniversary of the deadliest attack on U.S. soil, the last time as president, with a moment of silence at the White House at 8:46 a.m. EDT -- the exact the moment when terrorists crashed a hijacked airliner into the World Trade Center in New York. A second plane struck the trade center shortly thereafter. Another was flown into the Pentagon and still another crashed in a field at Shanksville, Pa.

"Thanks to the brave men and women, and all those who work to keep us safe, there has not been another attack on our soil in 2,557 days," Bush said.

Nearly 3,000 people died in the attacks, including 184 at the Pentagon where Bush spoke at an outdoor ceremony dedicating a new memorial to those killed there.

"For the families and friends of the fallen, this memorial will be a place of remembrance," Bush said. "Parents will come here to remember children who boarded Flight 77 for a field trip and never emerged from the wreckage. Husbands and wives will come here to remember spouses who left for work one morning and never returned home. People from across our nation will come here to remember friends and loved ones who never had the chance to say goodbye."

It wan Memorial, built at a cost of $22 million, contains 184 benches that will glow with light in the night, as well as trees and trickling water. Each bench is dedicated to an individual victim, and the structures are organized as a timeline of the victims' ages, moving from the youngest, 3-year-old Dana Falkenberg to the oldest, John D. Yamnicky, 71.

Andrea Earhart Stauter of Winchester, Ky., the sister of Edward Earhart, another Navy man who died at the Pentagon, said she now can mourn her loss at the new memorial and at a Kentucky cemetery where her brother is buried.

"We were one of the lucky ones to have a body to bury," she said.

Bush said the day will come when most Americans have no living memory of the events of Sept. 11.

"When they visit this memorial, they will learn that the 21st century began with a great struggle between the forces of freedom and the forces of terror," he said. "They will learn that this generation of Americans met its duty: We did not tire, we did not falter, and we did not fail."

His comment recalled his promise to the nation on Oct. 7, 2001, when the United States launched its strike against al-Qaida and the Taliban in Afghanistan. Bush said at the time: "The battle is now joined on many fronts. We will not waver; we will not tire; we will not falter; and we will not fail."

There was sort of a political time out on the campaign trail as Democrat Barack Obama and Republican John McCain agreed to appear together at ground zero in New York for a somber, silent wreath-laying there. They also suspended TV ads critical of each other.

Obama called on Americans to renew "that spirit of service and that sense of common purpose" that followed the terrorist assaults that killed nearly 3,000 people. McCain, in Shanksville, Pa., the site of a crashed plane, asked every person "to be as good an America roll call of the fallen and photographs of people in shock and grief. Moved by musical performances, Secretary of State Condoleezza Rice wiped tears from her cheeks. Afterward, Bush signed tiny American flags handed up from the crowd.

After the program, Mary Lou Moss of Saltillo, Texas rushed up to former Defense Secretary Donald Rumsfeld to show him a framed photo of her husband, Brian Moss, a Navy man who died in the Pentagon attack. "He's been through the whole thing with the families," she said of Rumsfeld, who was ousted amid growing opposition to the war in Iraq.

In his remarks, Rumsfeld said, "We will never forget the way this huge building shook."

Rumsfeld, who wore a sling on his arm from recent shoulder surgery, said it was at the Pentagon that the fate of the victims -- both on the ground and on the plane -- were "cruelly merged forever."

His successor, Defense Secretary Robert Gates, said that while the Pentagon represents U.S. military power, the memorial will be a remembrance of how "fanatiscism once laid it's terrible hand upon this building."

Security was tight throughout the ceremony and spotters were perched on the Pentagon's roof, watching the skies. During the program, a few passenger airliners made their descent into nearby Reagan National Airport.

Cassandra Castle of Winchester, Va., a friend of a victim, said something else gave her an even eerier feeling. Gray skies covered the event site, but off to one side, just above the memorial, was "the only spot of blue," she said.

The Pentagon Memorial, built at a cost of $22 million, contains 184 benches that will glow with light in the night, as well as trees and trickling water. Each bench is dedicated to an individual victim, and the structures are organized as a timeline of the victims' ages, moving from the youngest, 3-ited Airlines Flight 93 after they rose up against the hijackers.

Bush and British Prime Minister Gordon Brown spoke via secure video on Thursday morning. "The prime minister offered his thoughts and prayers to the president and the American people on the anniversary of Sept. 11," said White House spokesman Gordon Johndroe. Bush thanked Brown for Britain's steadfast support in the war against terror. "The two leaders discussed the need to remain committed to the fight against extremists," Johndroe said.