Last year at TED, Steve Rosenbaum shared this look inside the yet-to-open 9/11 Museum, filled with artifacts and stories from the people in the Twin Towers — the tower workers, the rescue teams, steelworkers, first responders, clean-up crews. The museum will be a powerful way to tell the stories from the attacks, and answer questions for a generation shaped by these events. As the Freedom tower rises on the site, the museum continues to develop below ground. But it has not yet opened; up to last night, there was a political stalemate around whether it would open at all and when. But on the evening of Sept. 10, an agreement was reached, and the project will move forward.

This morning, Rosenbaum sends this update and photo:

“I’m standing at the WTC site, with families, and with the memorial pools to my right and left. But underneath the plaza, the Memorial Museum is now once again under construction. In a year, if things move as planned the museum will be completed and the Memorial complete.”

Photo: Steve Rosenbaum

TED Blog exclusive video: Steve Rosenbaum takes us on a private tour of the 9/11 Museum, under construction now at the site of the World Trade Center towers. Below, he talks about why he joined the effort to create a memorial of the people and events of September 11, 2001.

Why did you decide to document the curation and construction of the 9/11 Museum?

On the day the towers fell, I was standing on my roof at 28th and 5th — and and I ended up working with a team of amazing filmmakers to record the day, and the week that followed. I made a film called “7 Days In September” and it always felt unfinished to me. Yes, there was 9/11 — but it seemed to me that history would care more about what happened next. So I just felt a strong call to go back, and be there with a camera to record what would happen and how the city would turn the anger into something important.

What’s the most surprising thing you’ve seen so far?

The Museum is underground, built to allow visitors to see the architectural heart of the story — the foundation of the Twin Towers. The space underground is massive, it’s a seven-story space, with 80,000 square feet of exhibition space. Visitors will see the crushed remains of FDNY Ladder 3, the towering “Last Column” and a number of other large artifacts. But I think the most surprising thing for me are the smaller artifacts and the human stories. I thought I’d heard every story possible, but time and time again the memories of those we lost are still haunting.

How do you think people will feel when they leave the museum?

I think that it will be a very emotional journey — and certainly painful at some points. But also inspirational in some ways that may surprise you. The Memorial Team talks a lot about building a living institution, and I think they’re accomplishing that. People will come from around the world. Adults who were teens ten years ago will come. People with different religious beliefs, different cultural perspectives, and different political and social backgrounds. The museum needs to speak to all of them, and tell the story without bias or an agenda. It’s huge complex task — but everything I’ve seen tells me that they’re accomplishing that.

When will it open, and when will your film be done?

There is no firm date, but the latest estimates I’ve seen say mid-summer 2013. There’s no doubt that the project has had to overcome some speed bumps and sort out some funding debates. But this isn’t something that should be rushed, or opened prematurely. It’s important they get the story right. The film has become more than a documentary — it’s a digital record of the process of the Museum’s construction and curatorial process. The people at the Museum have been generous and given me the opportunity to witness the complex and emotional construction process. And I’ve committed to not rushing the filmmaking. So, once the Museum is open, we’ll wrap our production and start post production. Probably a year or more after that.