The National September 11 Memorial Museum in New York was dedicated Thursday morning in front of an audience that included President Obama.
"It tells the story of how, in the aftermath of the attacks, our city, our nation and peoples from across the world came together, supporting each other through difficult times and emerging stronger than ever," said former New York City Mayor Michael Bloomberg, who is the museum's chairman. "That, more than any eulogy, was the greatest tribute we could pay to those that we lost."
Most of the museum is underground. To get there, you walk down a long flight of stairs, then down a winding ramp to the bedrock 70 feet below street level all the way down to the original foundation of the twin towers. After the attacks, this area became known as ground zero, where first responders and volunteers combed through the massive pile of rubble left after the towers collapsed.
"I was used to coming down here with boots on and stepping in mud and water," says Anthony Gardner, who lost his brother on Sept. 11. "And now it's this finished place."
Since Sept. 11, Gardner has pushed as an activist and a member of the museum's advisory council to preserve the buildings' foundation. He wants visitors "to stand within the actual footprints of the towers and be able connect to the people who died and connect to the experience of those of us who lived through Sept. 11 what we endured and how we responded."
The exhibits include massive steel fragments of the twin towers themselves, along with artifacts from first responders and office workers: photographs, video and hundreds of oral histories.
But the museum is more than just a chronicle of Sept. 11 and its aftermath. It also contains a memorial to the nearly 3,000 people who died that day and in the 1993 attack on the World Trade Center. And in another section off-limits to the public it houses the remains of some of the 1,100 World Trade Center victims that were never positively identified. A small but passionate group of family members continues to protest that decision.
Former New York Fire Chief Jim Riches lost his son, also a firefighter, on Sept. 11. He says, "This is the only cemetery that's going to charge admission in the whole world."
He and other families want to put the remains at street level, where the general public won't have to pay a $24 admission fee to pay its respects.
"It's outrageous," Riches says. "They're making money off my dead son."
Museum officials insist the majority of families are satisfied with keeping the remains below ground.
But that's one of many controversial choices the museum had to grapple with. It's also been criticized for including pictures of the terrorists who perpetrated the attacks, and for a seven minute video exhibit narrated by NBC's Brian Williams called "The Rise of Al-Qaida."
Arab-American groups are worried that some viewers may not get the message that al-Qaida is a radical fringe group and that it doesn't speak for the 1.5 billion Muslims around the world.
"What we think this film is going to do is potentially distort the image of Islam, which is something we've been working to fix for the past 12 years, since the day of Sept. 11," says Linda Sarsour, executive director of the Arab-American Association of New York.
But museum officials insist the language in the video was carefully vetted by curators and independent advisers, and that it's not going to change. They hope some of the criticism will fade as visitors finally get the chance to stand at the ground zero bedrock, but they seem resigned to the idea that it's not going away completely.
"The nature of this institution is looking at very hard things," says Paula Berry, who lost her husband on Sept. 11. "And so, I think, when you look at very hard things it is controversial."
Berry is now the co-chair of the museum's program committee. She says it will not be an easy experience for many visitors.
"It is not sugar coated. It's the facts," Berry says. "It would be wrong if it was any other way. But it's difficult, hard especially for a family member."
Family members are getting a first look at the National September 11 Memorial Museum Thursday. It opens to the general public next week.