The design objectives for the Sept. 11 memorial were specific: It would commemorate both loss and regeneration.
Today, 12 years after nearly 3,000 people died in the attacks on the World Trade Center, in Pennsylvania and at the Pentagon, the memorial plaza in lower Manhattan designed by Michael Arad and Peter Walker appears to have accomplished its mission.
Millions of tourists from all over the world have thronged to the site since it opened to the public two years ago. The waterfall-edged pools in the Twin Towers' footprints, each engraved with the names of the dead and surrounded by trees and rising skyscrapers, call forth reactions both somber and hopeful.
"It's amazing, just unbelievable to think they've rebuilt so much stuff in such a short period of time," said Madeline Wood, visiting from Cedar Falls, Iowa, with relatives. "It's just a wonderful tribute to the people who died here. It's like, we're coming back."
As with other historical traumas -- from the Civil War to Pearl Harbor and the Holocaust -- the memories of individuals pass with them into history. Those who study the forces shaping historical memory say that it is too soon to predict how 9/11 will emerge in the historical record, or in the collective memory of generations to come.
"The meanings and kinds of memories are evolving and will continue to evolve over time," said James Young, a professor at the University of Massachusetts Amherst, who studies the cultural and political forces shaping Holocaust memorials and was the sole historian on the committee that selected the 9/11 memorial design.
"The memorial is not over-determined so that it fixes memories, but allows future generations to come and find their own reasons for remembering," he said. "Really great memorials do that."
Nearing 'a tipping point'
The events of 9/11 are already moving beyond personal memory for many, said Civil War historian and Yale professor David Blight, one of the historians who have been advisers to the soon-to-open national Sept. 11 museum located at the plaza.
"We may be reaching a tipping point, 12 years out from the event," he said. "Now you have a lot of young people who don't have any real memory of this, and soon we will have millions with no memory. It will just be an event they hear about through time."
The memorial and 9/11 museum "will become a source of both refurbishing memories and creating them for a new generation," Blight said. How historical events are understood, he noted, depends on "how forthrightly we face the past and how closely we want to look at its causes and consequences."
He added, "Historical memory is always about the narratives we tell ourselves, the stories we believe in," conveyed to future generations in ways formal and informal -- from textbooks, media and political rhetoric to commemorations, rituals and family stories, shaped in part by those with the power to control how, and what, stories get told.
"It is quite possible that what we think we know about an event can be very different than truth," said Mark A. Greene, director of the American Heritage Center at the University of Wyoming, who noted that historical interpretations shift with the questions posed in different time periods, and the evidence available at the time.
For now, the narratives of those streaming onto the plaza are as much about pride and hope as they are about despair and loss.
As the waterfalls thunder into the reflecting "pools of absence" -- the water flowing and disappearing into a void at the centers of the pools -- the sounds of construction echo from striking new skyscrapers rising all around.
'We can stand together'
"It's inspiring and makes me feel pretty good about where we live, this country. Our biggest enemy poked us with a needle and we came back and made something beautiful. We're stronger now for what they've done," said Wood's grandson, Michael Best, 19, a college sophomore from Minnesota.
Best was in second grade on Sept. 11, 2001, and remembers the day as "very surreal. . . . The adults were crying and I didn't know why." He said he's had 12 years to sift through the "hysteria, the panic, the anger and all the sadness, and be able to take away something positive. Patriotism, community. . . . We can stand together when it counts."
Lisa Jones came from Connecticut with her daughter Molly, 19, and Molly's friend Lauren Dobrynski, 20, one day last month.
"I think it's a time of resilience in our history, finding a way to overcome," said Lisa Jones, 52. "That's what it stands for."
Her daughter, who was too young to have clear memories of the attack, said it was "something to learn from. Just because this happened we're not beaten. We keep moving. We'll still remember, but we keep moving."
And, said Dobrynski, "It brings us together. Even though we're from all around the world, we have this in common."
Tourists from all over the world come to the plaza. Michael Hadjitofi, visiting with his family from the United Kingdom, said the world suffered on that day. "There are very few events where the world can witness it live and that was unimaginable," he said.
New York University historian and museum adviser Edward Berenson said the memorial -- like the Vietnam Memorial in Washington, D.C. -- allows visitors to come together around the idea of bravery and sacrifice, whatever else their differences.
"That's really healthy for a society to be able to do that, but there should be a corner in our mind to remember our vulnerability as well, so we can better protect ourselves in the future," he said.
For now, despite persisting fears about terrorism, and contention over the wars and surveillance and privacy intrusions in the aftermath of the 9/11 attacks, people embrace the calming and healing and inspirational aspects of the memorial, the positive narratives gleaned from the loss.
Jamie Kennedy, visiting from Austin, Texas, with her family, marveled at the "tremendous progress" since first seeing Ground Zero in 2002.
"You can do nothing about a person blowing up a building. You can respond in a way that is uplifting, and empowering and supportive," she said. "There are many of us who would give their lives to help others. That's just who we are as a people."
The memorial, she said, is "perfect. The whole thing about putting water over fire is awesome. There's a little tear, but it's a calming, hopeful place."
She loved seeing the Survivor Tree -- a pear tree badly damaged by the 9/11 attack but nursed back to health and replanted on the plaza. "It's amazing that it would survive: You're not going to get us. You might think you will, but we will survive. And thrive."
Every day, tourists crowd around the tree as a guide recounts its story, showing photographs of the once-battered tree on an iPad.
Still, the presence of loss is inescapable.
Historian Edward Linethal, who has written of memorialization from battlefields to the site of the 1995 bombing of the federal office building in Oklahoma City, said he was struck by the insistence in so many memorial projects on the centrality of the victims' identities.
"It seems, perhaps, that this is a protest against the anonymity of mass death, an insistence that these people, these faces, names and stories will engage people's moral imagination by humanizing, in such a painful way, the enduring cost of violence," he said.
The interplay of loss and regeneration lies at the very heart of the memorial, said historian James Young.
"The taller the trees get, the deeper the volume of void gets, the deeper the loss. The taller the buildings, the deeper the canyon and void, that deep empty space," he said. "That will be the narrative, about resilience and regeneration all built around the core of loss."
The Ground Zero commemoration
The commemoration is for family members of victims of the 2001 and 1993 attacks and they have been invited to participate in this year's reading of the names.
8:46 a.m. Citywide moment of silence, observance of time first plane struck north tower. Houses of worship will toll their bells. Families of victims of 2001 and 1993 attacks will begin reading the names.
9:03 a.m.Moment of silence for when second plane struck south tower.
9:37 a.m. Moment of silence for when Flight 77 struck the Pentagon.
9:59 a.m. Moment of silence for when the south tower collapsed.
10:03 a.m. Moment of silence for when Flight 93 crashed near Shanksville, Pa.
10:28 a.m. Moment of silence for when north tower fell.
12:30 p.m. Program concludes.
Tribute in Light: The lights, located at West and Morris streets, will be on beginning at sunset Wednesday and will fade away at dawn Thursday. There will be no formal program.