Many visitors to the William G. McGowan Theater, which opens Sept. 10 at the National Archives, will assume that it’s a sensitive restoration of an auditorium that dates to the building’s 1935 opening. With its neoclassical detailing and red-and-cream color scheme, the 290-seat hall mirrors the dominant style of the Federal Triangle neighborhood.

Former regulars at the Archives’ now-resumed documentary-screening program, however, may have a few questions: What happened to the quaint fifth-floor hall where films from the Archives’ collection were previously shown? And what used to be in the space now occupied by the McGowan?

Archives Public Information Officer Susan Cooper has a succinct answer to the latter question: “Dirt.” The new theater, which lies below the ceremonial steps on the Constitution Avenue side of the building, is part of an underground addition designed to expand the Archives’ public areas.

The new auditorium was bankrolled with a $5 million grant from the William G. McGowan Charitable Fund, which was established by MCI’s late founder and plotted by local historicist architect Warren Cox in emulation of the style of original Archives designer John Russell Pope. “You don’t come in here and feel like there’s a modern building screaming at you,” says Cooper.

The McGowan has several advantages over its predecessor, including 100 more seats, better sight lines, and state-of-the-art technology for screenings, conferences, and TV broadcasts. According to theater manager and film programmer Tom Nastick, the screen can be retracted to provide room for panel discussions, and the projection system is of “archival quality,” so rare holdings from the more than 300,000 reels in the Archives’ film collection will not be damaged.

Still, Nastick concedes, the old auditorium had its charms. “I started as the projectionist at that theater around 1985,” he says. “It took me a long time to reconcile myself [to the McGowan].”

But in addition to technical improvements and added capacity, the McGowan is better sited for public use. The old theater was oriented to the Archives’ Pennsylvania Avenue side, which is used by researchers, rather than toward Constitution, where the public enters. “We wanted people to be able to walk freely through the new part of the building,” Cooper explains.

The official opening will be marked by a full day of historic documentaries that were often shown in the old venue, including 1936’s The Plow That Broke the Plains, 1942’s Prelude to War, and 1964’s Nine From Little Rock. “My philosophy is that we want to increase the visibility of the holdings of the National Archives,” Nastick says. “There’s a lot of creativity in the history of the government film.”

Future screenings will also include The Fog of War, which represents an even larger category of documentary: independently made films that rely on the Archives’ holdings.

“We like to think of ourselves as a showcase for documentaries,” says Nastick. That role will be significantly expanded by the new theater, which will have children’s programming and even a heightened sense of whimsy: During the weekend of Oct. 30 and 31, the Archives will present a “Seuss and Sousa Family Weekend,” celebrating the 100th birthday of Theodor Seuss Geisel and the 150th of John Philip Sousa—both former federal employees, Nastick notes.

As for what happened to the old theater, you can probably guess: It’s been converted to office space. —Mark Jenkins