[In remembrance of 9/11, we’re reposting a tour we did last year of the 9/11 memorial and museum at Ground Zero. ? Ed.]

“In 100 years, there won’t be anyone alive that experienced 9/11,” says Steven Davis, whose architecture firm, Davis Brody Bond Aedas, is designing the 9/11 Museum. “What will you tell them? And how will you tell them, to make them understand what happened?”

Davis spoke to Co.Design during a tour recently of the unfinished site, which is slated for completion on September 11, 2012–a scant two years from now, and eleven years after the Twin Towers fell.

Despite the museum’s unfinished form, a profound sense of what it will be emerges, because this isn’t your typical sort of building. Rather, it’s a processional decent into the gaping hole left by the towers–marked by reminders, both gargantuan and intimate, of what happened on the ground you step across. “Almost no memorial museum is sited where the tragedy actually happened,” says Davis. “And this museum is the reverse of most. Usually, the museum houses the exhibit. Here, the exhibit houses the museum.”

Design wise, the architecture firm’s chief goal was not to muddle the site with new architecture–but rather, to let the immensity of the site serve as a dramatic, natural testament to the events. “The first thing I heard from the Port Authority’s chief architect was, ‘You have to remember, this place is big,'” says Davis. “This space is really on the scale of urban design.”