It's a different kind of 9/11 commemoration: Ten years after four hijacked airplanes crashed and nearly 3,000 people died, activists are staging events across the country to denounce as lies the official accounts of what happened that tragic day.
The conspiracy allegations began flying even as firefighters were dousing the smoldering remains at Ground Zero -- and they endure a decade later despite investigations that have debunked them.
There's the conspiracy theory that a cruise missile – and not a Boeing 757 – struck the Pentagon and that Flight 93 actually was shot down over western Pennsylvania. And there's the claim that U.S. air defenses were ordered to "stand down" on 9/11, allowing the hijacked airliners to hit their targets.
And that's just for starters.
"Whenever I am asked to speak about 9/11, it's rare that I speak without some of these theorists showing up. It's always the same people. They always ask the same questions -- and then we move onto the next meeting," said former N.J. Gov. Tom Kean, the co-chairman of the 9/11 Commission.
"They are not bad people … they just have these views that I cannot understand at all."
Rep. Peter King, R-N.Y., chairman of the House Homeland Security Committee, is less diplomatic, charging that conspiracy theorists "trivialize" the "most tragic event to affect the United States."
"People making these claims are disgraceful, and they should be ashamed of themselves," King said.
Most truthers believe that elements inside the U.S. government planned the 9/11 attacks or allowed them to happen, to justify the invasion of Iraq. And this week they are trying to use the tenth anniversary of the attacks to convince more Americans to rally around their cause.
The group We Are Change says it is sponsoring a 228-mile walk from the Pentagon to Ground Zero "to help bring attention to the ongoing coverup."
Leading truthers from around the world have assembled in Toronto for a four-day 9/11 "inquest." They will try to convince a panel that includes an Italian judge, an urban planner from the University of Tennessee and a Canadian professor of psychology that the Sept. 11 attacks really were the product of a conspiracy.
And the organization Architects and Engineers for 9/11 Truth is screening a new movie in the U.S. and Canada showcasing their claim that explosives brought down the Twin Towers and a 47-story building that collapsed later that day, 7 World Trade Center.
Talk of conspiracies crackled as an overflow crowd of more than 150 people crammed into a tiny theater in New York City's East Village on Wednesday night for the movie's premiere.
"And on the tenth anniversary of 9/11, there just happened to be Flight 93 footage that emerged," one member of the audience said sarcastically to another. He was referring to a never-before-seen video that surfaced this week of the smoke rising from the Flight 93 crash site.
"Yeah, who is going to conduct a new investigation – the same people who did the first!"
An organizer took the stage. "Ten years. It's been a long time. A lot of familiar faces here," he said.
And then it was show time. The movie, "9/11: Explosive Evidence -- Experts Speak Out," is a 2-hour and 16 minute assault of ominous music and dozens of structural engineers and architects making allegations about a "travesty of justice" and "an orchestrated cover-up."
They cite evidence that they insist proves the buildings collapsed because of controlled explosions and not by fires that raged unchecked and caused the buildings' structural supports to weaken and fail.
Applause rippled across the theater when the lights went up. One audience member stood and spoke to the crowd. "There has to be a revolution in this country!" he said. "They are lying to enslave and manipulate us!" Heads nodded and hands clapped.
"I didn't know what I was coming to see. My friend dragged me here," Nydia Carrion, a billing supervisor from Long Island, NY, said as she headed into the rainy New York night.
"I think it is true what they are saying: The buildings were blown up," she said. "Asked who might be behind such a conspiracy, she said, "Probably the government, I hate to say."
Dr. Gene Corley, past president of the National Council of Structural Engineers Associations, led one of the forensic investigations of the World Trade Center collapse. He has not seen the movie, but said he familiar with its allegations.
"To some degree it is junk science; to perhaps a large degree it is ignoring science -- not facing the facts of what is there on the video footage, on the still photographs, the investigations of what really happened," he said.
"Popular Mechanics" examined the most persistent conspiracy theories, including the controlled demolition claim, in a 2005 book, "Debunking 9/11 Myths," and found no evidence to support any of them. The book has been updated and reissued, for the tenth anniversary of 9/11, to reflect the always evolving conspiracy claims, said the magazine's editor in chief, James Meigs.
"We take their best arguments and we fact check them. And again and again and again, we find out they are based on misconceptions and misreading evidence -- and in some cases they are made out of full cloth," he said.
Former New York City Fire Commissioner Thomas Von Essen, whose department lost 343 firefighters and paramedics when the 110-story Twin Towers collapsed, said he initially paid no attention to the conspiracy theories. His reactions now range from anger to disbelief.
"Our government … can be a very incompetent and inefficient government, but I don't think it is dishonest," he said, "and the way our media is in this country, I don't think you could get away with it."
The truthers are unbowed. At the New York screening of "9/11: Explosive Evidence -- Experts Speak Out," an organizer told the crowd that the facts were on their side.
"This is a very serious situation," he said. "This is not a problem of information. There is plenty of information. It's a problem of organization."