SHANKSVILLE, Pa. - This summer Pamela DiMarino, who grew up in nearby Johnstown, Pa. and now lives in Texas, brought her two children to the field that is the final resting place of 33 passengers and 7 crew members of United Flight 93.
"All those poor people died that day, but they died for us, and they saved a lot of lives," DiMarino said.
Those 40 people are credited with saving lives, because their rebellion thwarted the plan of four al Qaeda hijackers to steer their 757 jet to Washington, D.C., probably aiming for the Capitol building, on Sept. 11, 2001.
After learning about the plane crashes into the World Trade Center and the Pentagon that morning from phone calls to relatives on the ground, the passengers and crew of Flight 93 voted to storm the cockpit, not knowing if they would gain control of the plane.
"You just get a lump in your throat. I can't imagine making a phone call to my kids and telling them 'goodbye.' It's hard," DiMarino said,
"Just to know that you're about to give your life to save others, I mean, it's tough to do," her son Tyler said. "I don't think a lot of people could do it, but they did."
Stacey Wade and her husband, Scott, came to Shanksville from central Ohio to teach their kids about sacrifice.
"About how people used their phones and called their families and let them know what was going on, and they took down the hijackers," Wade said. "Pretty special."
One telephone operator heard passenger Todd Beamer famously say the words: "Let's roll."
"We can't afford to forget - not only the individuals, but their collective actions on that day," said Gordon Felt, president of Families of Flight 93.
Felt's big brother, Ed, a computer software designer, was one of a dozen on board who made phone calls from the plane. Ed Felt called 9-1-1 from a bathroom and spoke to police.
"While our loved ones lost their lives, we feel they won the battle," Felt said. His brother was 42, with a wife and three daughters. "To families certainly, it's our sacred ground, and it's a battleground."
Every day, hundreds of people trek to this rolling countryside in southwest Pennsylvania 80 miles from the nearest major airport, in Pittsburgh. It has become a pilgrimage akin to seeing Gettysburg.
Many visitors leave American flags and other tokens of respect. Ranger Barbara Black says the National Park Service has collected and saved 40,000 items left at the site.
United Airlines captain Brett Anderson left his cap, along with personal note to United 93 Pilot Jason Dahl. "Jason, working with you was always a pleasure," the handwritten note said. "You have a salute and release from guidance for the final time."
Vietnam veteran Tom Walker donated one of his two Purple Heart medals; a squadron of Army troops brought a brick from a Taliban compound they overran in Kandahar, Afghanistan. Three children from St. Paul, Minn. sent in a plaque with their painted handprints and wrote: "Thank you for caring, fighting, and dying for our future."
This weekend, the first part of a permanent memorial is opening with the names of the 40 inscribed on a white marble wall demarcating the plane's flight path.
A constructed pathway borders the sacred ground where the hijackers throttled the plane into the ground, a spot marked by a large sandstone boulder.
"This whole area is covered with human remains and parts of the plane," said National Park Service Superintendent Keith Newlin. "To this day, we still find plane parts."
The Park Service manages the site and oversees construction of the memorial. In 2009, the Interior Department secured federal ownership of the various parts of the 2,220 acre park - a space double the size of Manhattan's Central Park.
"That plane did not go any farther. It did not go to Washington, D.C., so that's why people want to come, and they want to see that spot," Newlin said.
The final piece of the memorial, which is designed by California architect Paul Murdoch, will be a 93-foot tower with 40 wind chimes, one for each passenger and crew member. With $10 million still to be raised, the memorial is on pace to be completed in 2014.
"What they did in 30 minutes is amazing," says Ken Nacke, whose older brother, Louis Joey Nacke, was one of the passengers.
"They were able to gain information, formulate a plan, voted on a plan, and acted that plan, put it in motion, and prevented a greater tragedy. All in 30 minutes. How amazing is that?" Nacke said.
Joey Nacke, a 42-year-old toy company executive with a wife and two teenage sons, was on the Newark to San Francisco flight for a business trip.
"Family was their motivation for them to do what they did," his brother said, because all they wanted to do was go home and have dinner with their family."
Click here to find out more about the Flight 93 Memorial.