Yesterday, a transportation planner named Matt Johnson sent D.C.’s modern architecture fans into a panic with one tweet. “WMATA is breaking the cardinal rule of Brutalism by painting the vault at Union Station,” he posted, attaching photographic evidence: a shot of one section of the arch in its original, murky gray next to another slapped with a fresh coat of hospital-white paint.

The howls of protest that followed (“THIS IS OUTRAGEOUS!” tweeted City Paper’s own Kriston Capps) may seem like an overreaction. After all, the interiors of Metro stations can be light-deprived and the vaults can appear grimy, so why not spruce them up? “Metro is in the process of painting the Union Station vault to create a lighter, brighter station environment for customers at our busiest station,” a spokesman explained to WAMU’s Martin Austermuhle.

But the painting of the station is a bad and worrying move for multiple reasons. First, as Johnson has already pointed out, dirt will show up prominently on a background of white paint. And once you paint something, you’ve basically committed yourself to repainting it for years to come.

Second, exposed concrete is integral to the Brutalist style in which the Metro system was designed. Contrary to critics of the style, the term “Brutalism” does not allude to any intent on the part of architects to “brutalize” the public with their heroic, muscular buildings. It derives from the French béton brut, meaning raw concrete. So covering up the surface of the concrete warps a fundamental principle of this design philosophy.

The Washington Metro is not a minor work of Brutalism, or of architecture full stop. In 2014, the system won the Twenty-five Year Award from the American Institute of Architects (AIA). This award is given to structures that have “stood the test of time” and “continue to set standards of excellence,” according to the AIA. Other buildings to have received the honor include Frank Lloyd Wright’s Guggenheim Museum and Mies van der Rohe’s Farnsworth House.

Even if you’re not a fan of Brutalism, you can imagine what an unsympathetic paint job might do to your favorite historic building. Just because the Metro is of more recent vintage than most landmarks doesn’t mean it’s less worthy of architectural respect. Plus, Union Station is one of the five “core” stations that opened on the original, much shorter Red Line in 1976. It seems reasonable to take liberties with newer stations, but those that most closely represent the vision of Metro architect Harry Weese (1915-1998) deserve special care.

There can be no doubt that whitewashing is hostile to Weese’s design and the ambience he created inside stations. That ambience owes something to Giovanni Battista Piranesi, an Italian artist of the 1700s. Piranesi is celebrated for his etchings of ancient Roman ruins, combining archaeological details with dramatic chiaroscuro, or the interplay of light and shadow. His etchings evoke a sense of wonder at the scale of monuments like the Roman Pantheon and the Baths of Caracalla. Weese’s genius was in coining a kind of Piranesian Brutalism that complemented, in a strange and powerful way, Washington’s above-ground neoclassicism. The coffers, or sunken panels, in Metro’s high vaults are shadowy cousins of those in the Jefferson Memorial (itself based on the Pantheon). Remember that concrete was invented by the Romans—and the Pantheon’s two-thousand-year-old concrete dome is brut (raw).

On a more visceral level, what can beat the sensation of descending into the cool, dim Metro on a blazing 100-degree day? The white tiles of the New York subway try to distract us from the knowledge of being underground, but D.C.’s Metro wants us to embrace that and enjoy it as a subterranean place apart. There is a reason that Instagram and Flickr are full of moody black-and-white photos of Metro stations: People love them as they are. (More frequent trains would be nice, however.)

Yes, WMATA needs to fix dark spots and general light levels in many stations—but slapping on some paint is a crude way to do it. Smart architectural lighting designers armed with LEDs can solve this problem. Metro leaders: Stop whitewashing Harry Weese’s masterpiece.

UPDATE: On March 31, the Washington chapter of the American Institute of Architects expressed “deep concern” over the painting of the Union Station vault. Mary Fitch, executive director of AIA DC, wrote in a letter to WMATA General Manager Paul Wiedefeld that the paint “not only interferes with the design character of the stations, it creates an additional maintenance requirement that the system can ill afford.” “We strongly urge you to stop the painting and to look for another solution that will not harm the look of the Stations nor cause a continuing maintenance cost,” she wrote. 

Also on March 31, the U.S. Commission of Fine Arts wrote to Wiedefeld noting that the standard review process for significant alterations to D.C. Metro stations had not been followed in this case, and instructed WMATA to suspend the painting “in order to assess its technical rationale, its aesthetic impact, and its long-term effect on the station.”