(AP) - Relatives of victims killed at the World TradeCenter arrived at dawn Thursday for ceremonies that willcommemorate the seventh anniversary of the Sept. 11 attacks andbring both presidential candidates to ground zero later in the day. Moments of silence were planned to mark the times that twohijacked jetliners crashed into the twin towers, along with themoments that the buildings collapsed. Services were also to be heldin Pennsylvania and at the Pentagon, where a new memorial will bededicated. Maureen Hunt, wearing a T-shirt with a picture of her sister,Kathleen, a 9/11 victim, said that it was comforting to be at theceremony with so many who have lost loved ones. "This is a place for us to meet," said Hunt, who has come eachyear to pay her respects. "It is not getting easier to attendthese ceremonies." She said she won't go down into the pit where the towers oncestood, and which some survivors consider sacred ground. It is now ahuge construction site. On Thursday, American flags were drapedover silent cranes. "Eventually, I hope that something gets built," Hunt said,referring to the long-stalled rebuilding of the site. This year the solemn events unfold amid a presidential campaign,with John McCain and Barack Obama scheduled to pay silent respectsat ground zero Thursday afternoon and later attend a New York Cityforum on public service. McCain was also attending Thursday'smemorial service in Shanksville, Pa., for the 40 people killedaboard the hijacked flight United 93. Family members and students representing more than 90 countriesthat lost victims on Sept. 11 were to read names of more than 2,700people killed in New York. Some mourners wondered if theremembrance would, or should, continue as it has indefinitely. About 3,500 people attended last year's ceremony, down about 25percent from 2006. "We've kept it alive, and perhaps kept it alive too long,"said Charles Wolf, whose wife, Katherine, was killed at the WorldTrade Center. "How many times do you reopen the wounds?" Wolf, who lives in downtown Manhattan, attends the ceremonyevery year but said it has become more painful, especially to standin silence for the moment that a plane crashed into the tower wherehis wife worked. "It's one thing to remember," he said, "butit's another to relive it." The ceremony moved to a park just east of ground zero last yearbecause construction at the trade center site makes it impossibleto have it there. But family members are allowed to descend sevenstories below ground to the site and touch the ground where theirloved ones died. The ceremony will include the reading of 2,751 victims' names,one more than last year. The city restored Sneha Philip, a womanwho mysteriously vanished on Sept. 10, 2001, to its official deathtoll this year after a court ruled that she was likely killed atthe trade center. McCain and Obama planned to visit the site after the ceremonyconcluded Thursday afternoon. The candidates agreed weeks ago topull their campaign ads for the day and were appearing togetherThursday night at a forum on volunteerism and service. Former Mayor Rudy Giuliani was to speak at the ceremony, as hehas every year in New York, along with officials including MayorMichael Bloomberg and Homeland Security Secretary Michael Chertoff. Last year's reading by Giuliani, then a Republican presidentialcandidate, drew strong protests from family members who said thecity was ill-prepared for the terrorist attack under his leadershipand questioned whether he should be there while running for theWhite House. They had no opposition to the presidential candidates' visitthis year. A family group opposed to Giuliani, a McCain supporter,sought a meeting with the Republican to urge him to sever ties withthe former mayor. In Pennsylvania, bells will toll for each victim killed onFlight 93. A similar ceremony is held each year in the isolated,reclaimed minefield where the aircraft came down after passengersreportedly stormed the cockpit. In Arlington, Va., Defense Secretary Robert Gates planned toattend the dedication of the first of the three major memorials tobe completed, at the Pentagon. The 2-acre park, located at the spot where American AirlinesFlight 77 crashed into the Pentagon's west wall, represents the 184victims with cantilevered benches in their name. President Bush and first lady Laura Bush will mark theanniversary during a moment of silence on the South Lawn. Memorials are years away from being built in Pennsylvania andNew York. The stalled, complex rebuilding of office towers, atransit station and memorial at ground zero prompted the governorto order a reevaluation of budgets and schedules for all projects.The agency that owns the site has said the 10th anniversary of theattacks may be too soon for the 8-acre memorial planned in NewYork. As in past years, two bright blue beams of light will shine atnight on the New York City skyline, in memory of the fallen towers.