Friends and relatives of the victims of the Sept. 11, 2001, attacks gather Thursday during the playing of the national anthem at New York City's Zuccotti Park on the seventh anniversary of the terrorist destruction of the World Trade Center.

Military personnel stand ready to remove the covers of the individual memorial benches Thursday during the dedication ceremony of the Pentagon Memorial, the first permanent memorial to the victims of the Sept. 11, 2001, terrorist attacks. The memorial includes 184 benches that will glow at night, one for each victim there.

New York ? Familiar rituals of grief marked the seventh anniversary of Sept. 11 on Thursday as thousands paid tribute at the attack sites, the presidential candidates laid flowers at ground zero and children mourned parents they can barely remember.

Sens. John McCain and Barack Obama called off their campaigns for the day, and in the late afternoon descended the long ramp into the pit of the World Trade Center site, bowing their heads and leaving the flowers in a reflecting pool.

At the Pentagon, 15,000 people turned out for the dedication of the first permanent memorial built at any of the three sites where hijacked planes crashed. It includes 184 benches that will glow at night, one for each victim there.

“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,” President Bush said at the outdoor dedication.

In New York, the crowd fell silent in a park just east of the trade center site at 8:46, 9:03, 9:59 and 10:29 a.m. – the times when two hijacked jets slammed into the buildings and the twin towers fell.

Alex, Aidan and Anna Salamone – now 13, 11 and 10 years old – wore old soccer jerseys belonging to their father, broker John Patrick Salamone, who was 37 when he was killed. They recalled playing in the yard with a toy wagon.

“He was strong. He was funny. He always made me laugh,” Alex Salamone said. “I wish I could remember more, but we were so young when he died.”

Still others chose to forgo the public observances altogether and mark the day in quieter, more private ways. Kai Thompson Hernandez toasted her late husband, Glenn Thompson, at a beach, with his favorite brand of beer.

“I try and celebrate his life rather than mark the place of his death,” she said.

Family members of the trade center dead and students representing the more than 90 countries that lost citizens in the attack – Azerbaijan to Zambia to Vietnam – read the names of the 2,751 victims killed in New York.

Others descended seven stories below street level to pay respects where the towers once stood. A giant crane, an American flag hanging from a hook, overlooked the anniversary ceremony from ground zero, where office towers, a memorial and transit hub are under construction.