On a clear day, like the one when terrorists with hijacked planes changed the world, survivors of the Sept. 11 dead gathered at ground zero to recite loved ones’ names, hold up their photos and talk about the children they left behind.

“I see your face in little Joseph’s smile and I feel your touch in his hugs,” Lisa Reina said, addressing her slain husband, Joseph Reina Jr.

At sunset, two blue beams of light filled the sky to evoke the towers of the World Trade Center.

The city’s tributes were the focal point of remembrances across the country Monday as the nation marked the fifth anniversary of the attacks that killed nearly 3,000 people in the nation’s capital, its largest city and in a remote Pennsylvania field.

Americans held “freedom walks,” gathered around flags, and tolled bells. After a tear-filled ceremony in Maine, participants filed into the state Capitol to see a memorial made with a section of a girder from the trade center. In Ohio, fire truck sirens wailed and college students planted thousands of flags across the state.

Hundreds gathered in a wind-swept field in Pennsylvania to remember United Flight 93, and the president and first lady ate breakfast with New York City firefighters before placing a wreath near a plaque outside the Pentagon.

In a prime-time address later Monday, the president characterized the war against terrorism that followed the attacks as a “struggle for civilization.”

“We are fighting to maintain the way of life enjoyed by free nations,” Bush said.

At the nearly barren 16-acre expanse at ground zero, four moments of silence observed the moments when jetliners crashed into the twin towers and the skyscrapers crumbled to the ground.

The painfully familiar task of reading the names of the 2,749 trade center victims fell this year to their husbands, wives and partners, who personalized the roll call with heartbreaking tributes to the loves of their lives.

“If I could build a staircase to heaven, I would just so I could quickly run up there to have you back in my arms,” said Carmen Suarez, wife of police officer Ramon Suarez.

Christina Lynch mentioned her daughter, Olivia. Sheila Martello mentioned her two sons, Thomas and James. Richard Pecorella spoke to his fiance, Karen S. Juday, about heaven. “Baby, I love you. Save a spot for me,” said Pecorella.

“I miss you, sweetie. And I thank you for what you have taught me in my life,” said John Winter, who lost his life-partner, William Karnes.

A choir performed the national anthem, and then the sound of bagpipes — so familiar after the funerals of the Sept. 11 dead — echoed across ground zero.

Family members descended into the pit 70 feet below ground where the towers stood, tearfully laying wreaths and roses in reflecting pools in the skyscrapers’ footprints.

The ritual has changed little since the first anniversary of the attacks, and in many ways the site has remained the same as well.

Squabbles over design and security have caused long delays in the project to rebuild. Train service returned three years ago, but only this year did construction start on a Sept. 11 memorial and the 1,776-foot Freedom Tower, which is not expected to be finished for five more years.

“The terrorists did win to a point, because there’s still arguing and fighting,” said Diana Kellie, whose niece was killed, as she peered down at the site. “Five years later, there should have been something in here.”

After observing moments of silence in New York at a downtown firehouse, Bush laid a wreath at the Shanksville, Pa., field where Flight 93 crashed, and privately greeted relatives of the 40 people killed.

“One moment, ordinary citizens, and the next, heroes forever,” retired Gen. Tommy Franks said, alluding to the passengers who apparently forced the hijackers to crash the plane.

The president and first lady then traveled to place a wreath outside the Pentagon, where the crash of an American Airlines jet killed 184 people. Bush appeared teary-eyed as he greeted victims’ family members around him, and he could be seen mouthing “God bless you” as he embraced them.

The day was marked by reminders of the tense new realities of color-coded alerts and fears of the next attack, particularly on the nation’s transit systems. New York’s Pennsylvania Station was briefly evacuated because of a suspicious duffel bag that turned out to hold only trash.

A jet bound for San Francisco was diverted to Dallas after a backpack and handheld e-mail device were found on board, but both items were pronounced harmless.

In a new video, al-Qaida’s second in command warned of forthcoming strikes in the Persian Gulf and against Israel.

At Boston’s Logan Airport, security screeners wearing wristbands reading “We will never forget” stopped checking passengers for a moment to mark the anniversary, and travelers waiting in line paused to join the tribute.

At a ceremony outside an elementary school in Mascoutah, Ill., not far from Scott Air Force Base, Lt. Col. Jim Williams praised first responders.

“I’m in the military and defend the country, but only in certain times,” he said. “They do this every day.”

In Akron, Ohio, firefighters rolled their trucks out of their garages and sounded their sirens for 30 seconds at the moment the south tower of the trade center collapsed, and again half an hour later for the north tower. Chicago firefighters and their families read the names of the 343 firefighters who died responding to the attacks.

The families of the dead made their way through ceremonies as well as they could, the rituals now familiar but never easy. They wore T-shirts and buttons and blew kisses to the sky as they said their goodbyes for another time.

“We love you, T,” said Pat Hargrave, who lost her husband, Timothy John Hargrave, at ground zero. “As you would say to everyone, ‘Peace.’”