Plaster walls inside 2318 18th St. NW, in the Adams Morgan section of the District, reveal graffiti from a time when the building was home to an artists’ co-op that provided a venue for punk bands.) (John Kelly/The Washington Post)

A few months ago, local filmmaker James Schneider was walking in Adams Morgan when he saw that workers were renovating 2318 18th St. NW. Schneider walked up the metal stairs to the first-floor entrance and talked his way inside.

The interior drywall had been removed, revealing plaster-covered brick walls. Schneider was amazed to see that the long-hidden plaster had been daubed with prehistoric paintings of bison, horses and aurochs.

No, just kidding. But the newly revealed images are sort of the Lascaux cave paintings of the D.C. punk music scene. The walls are covered with graffiti from the townhouse’s time as an artist cooperative known as Madam’s Organ, a hot, sweaty incubator that in 1979 and 1980 helped birth the city’s hardcore punk movement.

The graffiti includes the names of such bands as the Bad Brains, Trenchmouth, the Penetrators, the Slickee Boys, the Teen Idles, the Nurses, Tru Fax & the Insaniacs — a veritable who’s who of early D.C. punk.

“When I saw the actual list of bands, I nearly fell off the ladder, because for me this was sort of the El Dorado of graffiti in there,” Schneider said.

Schneider had a feeling the graffiti would be there. For several years, he’s been working with Paul Bishow on “Punk the Capital,” a documentary that focuses on the Madam’s Organ scene. Bishow attended shows at Madam’s Organ, capturing them on Super 8 movie film.

Madam’s Organ was founded in the early 1970s as a co-op by students from the Corcoran School of Art. It soon became a yippie hangout and performance space, a place of experimentation of all forms. Schneider wasn’t around for that scene — he’s in his 40s — but many of the graying punks he interviewed for the film had strong memories of Madam’s Organ.

“There was sweat just dripping off of everywhere, probably,” he said. “People talk about the contact high from pot smoke, cigarette smoke. Everything went on in that building at Madam’s Organ. It wasn’t a place that said no to the kids — or to any other activity. It was really a free space like we don’t see so much of these days.”

Or, as Nurses bassist Howard Wuelfing put it in the book “Dance of Days,” by Mark Andersen and Mark Jenkins: “Madam’s Organ was creepy, smelly and badly run. Everyone was always pissed off at how bad the sound was.”

And yet, as Wuelfing admitted, “Madam’s Organ gave a lot of bands a reason to form in the first place, just because it was a place to play. There weren’t many of those at the time.”

It wasn’t just punk bands that performed at Madam’s Organ, which should not be confused with the bar and nightclub across the street. At least as chronicled by the Magic Markered roll call of names on one wall, rockabilly Tex Rubinowitz and the Bad Boys played there. So did surf revivalists the Insect Surfers, the poppier Nightman and a synthesizer player named Rupert, who performed wearing chain mail.

Other graffiti includes “Freedom is the recognition of a necessity” and, in blue spray paint, “Energize your boots.”

There are also some naughty words.

Schneider returned with a conservator to see what it would take to remove the plaster. He was told it would be expensive and time-consuming. The plaster was troweled directly onto the brick walls, making removal difficult. But Schneider said “Punk the Capital” should be completed this winter. Music buffs will then get a chance to experience Madam’s Organ.

I stopped by 2318 18th St. last week. The contractors were awaiting city inspectors. They told me that they hadn’t heard of any of the bands, but they seemed amused by some of the names and tickled that they’d uncovered a bit of history. Though the plaster won’t be removed, it won’t be harmed either, they said. Commercial construction requires that walls be built out from the brick, meaning the space will be framed in, the graffiti sealed up safely.

The space most recently was a hair salon. It will become Insomnia Cookies, a bakery that delivers cookies till 3 a.m. Fittingly, it will sit above Wash Hydro, a store in the basement that sells marijuana-growing equipment. Munchies and munchies-eradication in one convenient spot.

During my visit, I snapped a bunch of photos, then went two doors down the street to Smash, a record store specializing in punk and alternative LPs, CDs and clothing. I pulled out my digital camera and showed the pictures to Kohei Urakami, the store’s 22-year-old clerk.

“That’s archival,” he said, impressed. “That should be preserved or documented.”

In a way, it is. The best documents are the songs.

Twitter: @johnkelly

For previous columns, visit washingtonpost.com/johnkelly.