The following script is from "The 9/11 Museum" which aired on April 21, 2013, and was rebroadcast on Sept. 8, 2013. Lesley Stahl is the correspondent. Shari Finkelstein, producer.
Each year as the anniversary of Sept. 11th approaches, we remember the events of that awful day and honor its victims. Next spring, at ground zero in New York City, one of the largest and most ambitious memorial museums in the world is scheduled to open its doors to do that permanently -- the National September 11 Memorial Museum.
It'll actually be located below ground -- seven stories down. It's a project that's been plagued by delays, funding battles, even a flood thanks to Hurricane Sandy. But if you can believe it: those things were the easy part. The bigger challenge: how do you convey the horror of 9/11 without making it unbearable? Memorialize a day most of us wish we could forget?
Tonight we'll take you down below, as we first did last April, for an in-depth look at what our nation's 9/11 Museum will be.
Ground zero above ground is today a place of rebuilding, and remembrance. At its center is a serene memorial plaza with two giant cascading pools -- twin voids set into the footprints where the towers of the World Trade Center once stood. Each pool is surrounded by names - 2,983 of them -- plus some who didn't even have a name.
It's quiet and powerful as people come -- over 10 million so far -- to touch and feel and in some cases mourn fathers, sisters, children. But you won't find anything here about what actually happened on 9/11; nothing about the buildings, the planes, nothing about the terrorists. All that will be the job of the museum, and its director Alice Greenwald.
Alice Greenwald: We occupy literally the space below the Memorial Plaza.
Lesley Stahl: So we're walking--
Alice Greenwald: --you're walking on the roof of the museum.
This is not Greenwald's first job on a project about a painful subject. She came here from the Holocaust Museum in Washington, D.C.
Alice Greenwald: Just watch your step, Lesley. It is a construction site.
But at this construction site, the issues go far beyond where to put the walls. Virtually every decision here is fraught with meaning, as you descend past two 50-ton beams recovered from the wreckage into a space...
Alice Greenwald: Welcome to Foundation Hall.
...that takes your breath away.
It's haunting and a little chilling knowing you're in the belly of ground zero. In the place where so many innocent people lost their lives.
Lesley Stahl: So here we are, we're right where the buildings collapsed. We're in it.
Alice Greenwald: Most museums are buildings that house artifacts. We're a museum in an artifact.
Lesley Stahl: Where we are is almost sacred.
Alice Greenwald: I think you are become super conscious of where you're standing. And that's a powerful thing. It's a very powerful thing.
Anthoula Katsimatides: It's the authentic site of loss.
Monica Iken: It is sacred and hallowed space.
We spoke with four family members who are also members of the museum's board. Paula Grant Berry's husband, David, worked in Tower 2, as did Monica Iken's husband, Michael. Anthoula Katsimatides's brother, John, was in Tower 1; and Tom Rogér's daughter Jean was a flight attendant on American Airlines Flight 11.
Paula Grant Berry: The site radiates something for us all in a very special way.
Monica Iken: That's where the final resting place of our loved ones is.
Lesley Stahl: It has to be there?
Monica Iken: It has to be there.
Voices: Has to be there.
Anthoula Katsimatides: Yes.
Monica Iken: And you can feel it.
Alice Greenwald: This is the remnant of the exterior structure that made up the twin towers.
One of Greenwald's first challenges, in this hallowed space, was deciding where the story of 9/11 should begin.
Alice Greenwald: We begin with the voices of people from around the world remembering where they were when they heard about the attack.
[Someone barged in and said, "Oh my God, a plane has just crashed in to the World Trade Center.]
The idea is to acknowledge that most visitors will bring their own memories of 9/11, which was witnessed within hours by people all across the globe.
[Phone rang, woke me up, my business partner told me to turn on the television]
Greenwald says we are all survivors of 9/11, so it's fitting that visitors will descend to the main exhibits of the museum beside an enormous staircase, now encased in wood, that served as an escape route.
Alice Greenwald: On 9/11, hundreds of people ran to safety down this stair.
The so-called "survivor staircase" is one of several artifacts so big the museum had to be built around them -- like this fire engine lowered in through a hatch in the roof that will honor first responders, 441 of whom lost their lives. And the famous last column, the final massive remnant of the towers to be removed from the site.
But we found that some of the most powerful things on display here...
Lesley Stahl: OK, so that's Flight 11.
Alice Greenwald: Takes off from Boston.
...won't be physical artifacts at all.
Lesley Stahl: Oh look, the second plane...
A large projection on the wall will show the morning of 9/11 as it played out in the air.
Alice Greenwald: Flight 11 is hijacked. Meanwhile, Flight 77 leaves.
...With the simultaneous flight paths of the four planes.
Alice Greenwald: And now, Flight 93 takes off. Impact has already happened in New York.
Lesley Stahl: Oh, look at this.
Alice Greenwald: And then Flight 93 is hijacked, turns around.
Among the agonizing decisions for the museum: Should they include the voicemail messages left by passengers aboard those planes -- and other victims of 9/11 -- for their loved ones? One adviser told Greenwald to think of these recordings as a form of human remains.
Alice Greenwald: What he said, and I've never forgotten it, is that sound can be a more emotional form of communication because you hear the timbre of the human voice.
[CeeCee Lyles (audio): Baby you have to listen to me carefully. I'm on a plane that's been hijacked.]
They plan to include a few recordings, seek permission from family members, and use them only with a purpose: this one, from flight attendant CeeCee Lyles to her husband, as a testament to the professionalism of the hijacked crews.
[CeeCee Lyles (audio): There are three guys. They've hijacked the plane. I'm trying to be calm.]
Alice Greenwald: She is so composed.
Lesley Stahl: She's in flight attendant mode.
Alice Greenwald: She's in flight attendant mode. And at the very end of the call she says something like-- "I hope I see you again, baby."
[CeeCee Lyles (audio): I hope to be able to see your face again, baby. I love you. Bye.]
Lesley Stahl: Oh my goodness.
And, of course, audio is just the beginning of the sensitive questions about what should be exhibited.
Lesley Stahl: Let me ask you. What about some of the horrific shots for example of people jumping?
Alice Greenwald: This is probably, as far as I'm concerned, the most sensitive question for this museum.
Joe Daniels: We went through a lot of debate internally about, "Do we show that side of the story?"
On the morning of September 11th, Joe Daniels came out of the subway to the gruesome sight of bodies falling from the North Tower. Today, he is president of the 911 Memorial and Museum.
Joe Daniels: You never want to have to see that; someone 100 stories up, 1,000 feet in the air, having to make that kind of choice. On the same time, there's a very strong feeling that this was a part of the story, that a group of people from this group, al Qaeda, put innocent people in a position to have to do that.
Lesley Stahl: When you think about what terrorism means, this really says it.
Alice Greenwald: Absolutely. It's an impossible thing for a human being to do to another human being. And yet, it became possible on 9/11. So for us not to acknowledge that would be to not be true to the story.
But how? With video of people falling, or photographs? And what about the feelings of family members? Greenwald told us that she knows that some will never want to see an exhibit on this subject, but many argued strongly that it had to be there...
Alice Greenwald: I have to say that we were also-- I don't want to say accosted, that's a little strong. But, you know, shaken by the lapels by family members who said, "You have to tell the story. Don't whitewash the story. Tell it like it was. The world needs to know."
Joe Daniels: So we ultimately decided that we will include an exhibit,// but do it in a way, in an alcove, where people will be clearly warned, and if they don't want to see it or have their family see it, they can easily avoid it.
One exhibit they want everyone to see is what Greenwald calls the heart of this museum: a space devoted to honoring the victims lives with photographs of each of them lining the walls.
Lesley Stahl: Those giant walls out there go all the way up. Every bit of space will be covered--
Alice Greenwald: Right.
Lesley Stahl: --with faces?
Alice Greenwald: Yes. The impression will be that you are surrounded by nearly 3,000 faces.
These are the photographs that will cover those walls.
Lesley Stahl: Look at those faces. Look at all those faces.
Alice Greenwald: They're ages two and a half to 85, from over 90 countries, every sector of the economy. Every possible ethnic group.
Visitors will be able to search these interactive tables and call up profiles of each person, with photos and recorded remembrances by family members and friends like this one by the father of Paul Acquaviva, who died in Tower 1.
[Mr. Acquaviva: He never had a bad word, literally, to say about anybody. He always looked at the positive. You know, I know, to be honest with you, he didn't get it from me, 'cause I'm very critical at times. To me, that was one of the most important things about Paul. ]
Alice Greenwald: Some of them are funny. Some of them are sweet. And we're not telling you who they are, their loved ones are telling you who they are.
Visitors can also search by birthplace, or by company.
Alice Greenwald: If I call up Cantor...
Cantor Fitzgerald was the company that lost more employees than any other.
Alice Greenwald: 658 people--
Lesley Stahl: Look at that--
Alice Greenwald: --who died on 9/11 at Cantor Fitzgerald--
Lesley Stahl: From that one company.
One of the 658 was John Katsimatides, Anthoula's brother.
Anthoula Katsimatides: So there's four of us growing up, George, John, myself, and Michael.
We were there the day she brought photos to contribute to John's profile to the museum's chief curator.
Jan Ramirez: Well that is just so cute.
Anthoula Katsimatides: I know.
Lesley Stahl: What's it like to go through the photographs and choose?
Anthoula Katsimatides: I had an extremely difficult time doing that. Because, you know, you see him as a child growing up, you know, and then as a best man in all of his best friends' weddings. So it's like, well, which one do you pick, because you just are so sad that the pictures stop here.
Families members all share the devastation of their loss, but the museum discovered that they are hardly a monolithic bloc.
Alice Greenwald: It's the families of nearly 3000 people. It's, you know, probably 10,000, 20,000 people, all of whom have their own perspectives, their own desires, their own ideas about what kind of museum should be here.
Lesley Stahl: Was absolutely every single tiny little thing an argument?
Paula Grant Berry: There were lots of issues.
Monica Iken: Oh boy. Lots, lots.
Like whether to exhibit pictures of the perpetrators. And what about Osama bin Laden? Do they belong in the 9/11 museum?
Lesley Stahl: Well, what was the argument for not showing Osama bin Laden?
Joe Daniels: That on this-- this actual ground where the atrocity took place, this graveyard to some extent, how could you demean the memory of my loved one by showing the image of the person that murdered him?
But other family members took the opposite view, demanding accountability.
Anthoula Katsimatides: It was absolutely important to point fingers.
Monica Iken: You have to tell the story.
Anthoula Katsimatides: You know, we had to express who did this to our loved ones.
Joe Daniels: We don't want any child or adult or student to walk through this museum and not leave knowing who did this to us, which is why we're gonna go ahead and show those images.
But the museum also wants people to know the stories of heroism and selflessness, the spirit of unity after the attacks. So there will be tributes here to recovery workers and volunteers. By the time this museum opens its doors next year, virtually no one under the age of 17 will have a first hand memory of September 11th, 2001. For almost a quarter of the population 9/11 will not be a searing memory, it will be, well, something to learn about in a museum.
Anthoula Katsimatides: We are worried about the children who don't remember 9/11. And this is the way to tell exactly what happened to future generations so no one ever forgets.
Lesley Stahl: Even the painful, maybe most particularly the painful?
Paula Grant Berry: Right.
Anthoula Katsimatides: We're not talking about a simple little happening. You know, we're talking about a brutal attack on our country. You know, where 3,000 people were innocent, and they were murdered that day.