Bill Gallagher’s first job out of college was designing Metro stations.

He started work the month that Washington, D.C.’s Metrorail opened in 1976. Beyond the system’s five inaugural stations downtown, everything else was either under construction or on the boards in the offices of Metro’s late architect, Harry Weese, Gallagher’s first boss.

As the principal for KGP design studio, Gallagher still designs Metro stations today: His firm’s work includes canopies, elevators, and entrances for at least a dozen stations. His opinions about the system are both fiercely held and hard earned. So when he heard that workers were throwing a coat of gleaming white paint on Union Station’s exposed concrete vaulted ceiling—a signature Metrorail design feature—he was stunned.

“It was just unbelievable,” he says. “Absolutely shocking.”

Martin Moeller, senior curator for the National Building Museum, couldn’t believe it either. Washington Metropolitan Area Transit Authority has painted Metro’s vaults before—at Farragut North Station, for example, an episode that caused a fuss in 1992, as well as six other stations over the years. The Farragut North job was a light gray, Moeller recalls, close to the color of concrete.

“But not white,” Moeller says. “I’m sort of hoping against hope that it’s maybe a primer.”

“White would be a radical change,” Moeller adds.

It’s paint. It’s practically a declaration—and one that took WMATA’s own design team by surprise. Neither Metro chief architect Ivailo Karadimov nor Metro architectural historian Jeff Winstel were involved in the decision to paint Weese’s Brutalist vault white. They weren’t aware it was happening, according to a source, who was not authorized to speak for WMATA. (A spokesperson there could not confirm or deny the claim.)

What might be an exercise in eye-rolling for some Washingtonians (OK, most of them) prompted angst and anxiety for designers, historians, and fans who hold Metro’s design close to heart. Boosters of Brutalism—the little-loved modernist style marked by exposed concrete and a disdain for ornamentation—saw the paint job as more of a hatchet job.

But the arching walls of Union Station, the system’s busiest, were grim, grimy, and bleak. WMATA’s solution: several layers of white paint that will go up over the next few weeks. “While power washing was considered, years of dust, dirt, and grime coating the vault cannot effectively be cleaned and does little to move the needle when it comes to brightness,” WMATA spokesperson Dan Stessel says via an email.

The shine may not last. Metro’s vaults were not designed to be painted, according to Gallagher, and WMATA management made a mistake by not consulting the experts first. Raw concrete is a more forgiving surface, he says; it disguises wear and tear. Painting the ceiling in pristine white might look great at first, but will only highlight the fresh grime as it accumulates.

“You’re going to see every little problem in the future,” Gallagher warns. “Especially this station. It’s going to be filthy within weeks.”

Painting the station also runs counter to a couple of different efforts by WMATA. The agency is working with the U.S. National Park Service and the General Services Administration to come up with a more efficient way to clean exposed concrete (of which there is a lot in This Town.) There are no plans to paint other Metro vaults, according to WMATA, making Union Station a one-off job. Puzzlingly, WMATA is simultaneously preparing to submit a bid to add Metro to the National Register of Historic Places—a designation that would preclude any makeovers at all.

It’s all too common for institutions to come to think of their design features as flaws, says Robert Bruegmann, author of The Architecture of Harry Weese. The architect died in 1998, long enough ago for many at WMATA to have forgotten him. Elite opinion hasn’t turned on Weese: The American Institute of Architects granted Metro its prestigious 25-Year Award in 2014. [UPDATE 3/31: The D.C. chapter of the AIA issued a letter “expressing our deep concern regarding WMATA’s decision to paint the interior of the Metro Stations [sic] bright white.”]

Some of the more elegant strokes are easier to miss. Deep coffers that run between the ribs of the vaults—the coffers are structural, not decorative components—are mirrored by the shape of the windows on the older-style Metrorail trains.

Popular opinion has not held up so well, for a number of reasons—including neglect at every level.

“It’s very painful to see what happens when buildings and pieces of engineering like [Metro] get to be middle-aged,” Bruegmann says. “Everyone was just thrilled with that system when it opened. There was hardly any negative press at all. Then you get to a certain point. Little annoyances, lack of maintenance, changing standards as a system ages—that’s really the danger point.”

Instead of retooling Weese’s design, which WMATA has tried and failed at before, the agency could have just power-cleaned Union Station. It is already working to modernize Metro’s light conditions with technology that wasn’t around when Weese (and lighting designer William Lam) first designed the system in the 1960s. Simply by “relamping” its Metro stations, Gallagher says, WMATA can brighten murky platforms, bring down costs, and expand the maintenance window for lighting from every 2 years to every decade. (That would be a better use of the agency’s energy than, say, mucking with the kerning of Metro’s perfect Massimo Vignelli-designed signage.)

Exposed concrete was key to the kit of parts that Weese designed for Metro. He used a limited palette of durable yet warm materials, Gallagher says, among them quarry tile, granite, bronze, and brown paint (the color that best conceals rust on trains). No columns, so people can always see their path. Indirect lighting, so people can always see faces around them.

Not all of Weese’s concepts were flawless. The bronze elevators were dark and confining. (Gallagher’s firm replaced the one at the Rosslyn Metro Station with a more inviting glass elevator.) Huge station kiosks serve as forbidding barriers that divide station operators from passengers. There are kinks. But Metro’s warmth and awesome pitch are one of the best things about D.C., period.

“Harry Weese was a very fine architect, and he did quite a few buildings, many of them interesting and whimsical,” Bruegmann says. “Ironically, it was when he did the Metro, where he had the weight of all these commissions and bureaucracies to deal with, that he somehow managed, along with everyone else involved, to create this system.”

It is easy for commuters to take the visual achievement of Metro for granted. Especially when it’s on fire, or they’re stuck at Rosslyn waiting to pack like sardines onto a Blue Line train, or they’re cursing Metro’s name at Nationals Ballpark when service ends before the game does. But find a local photo fair that doesn’t include one photo of a blurry train against the majestic beige backdrop of Weese’s structural vault. Good luck with that.

WMATA can’t afford to take Metro for granted. The agency has more pressing matters on its agenda than cosmetic fixes; even allowing aesthetic concerns their due, WMATA appears to have pushed ahead without consulting any designers. That’s the kind of strategic thinking that’s blown up in the agency’s face over the years. WMATA seems to have found a problem in the one place in Metro where there wasn’t one: Weese’s design.

This article first appeared on CityLab. View the original story.