Sometimes a project’s greatest challenge is to create a sense of character where there isn’t much. Such was the case when a client called on Thomson & Cooke Architects and interior designer Zoë Feldman to revamp her ’90s-era townhouse in DC’s Foxhall enclave.

“It was a nice blank space, but underwhelming in architectural value,” Feldman recalls.

The owner, who’d just returned from a stint in California, sought a Spanish Mediterranean vibe. Another jumping-off point for the primary bath was the Greenwich Hotel, her favorite destination in New York, which boasts luxe, marble-and-brass-appointed bathrooms.

The team took the interiors down to the studs. Armed with inspiration, Feldman conjured an Old World-style bathroom complete with a tub for two, a large shower with an arched opening, a water closet, Carrara marble surfaces and unlacquered-brass fittings that will patina over time. Built-in cabinets keep clutter at bay.

A marble ledge by the tub is a resting spot for wine, candles or bath salts, says the designer, who had the walls coated in blush-colored plaster. “When done properly,” she avers, “plaster is even more waterproof than tile or stone. It also adds texture and really softens a bathroom.

“It is amazing,” Feldman concludes, “how a few architectural tweaks and treatments can make a room feel timeless and give it soul.”

CREDITS + DETAILS—Interior Design: Zoë Feldman, Zoë Feldman Design. Renovation Architecture: Neal Thomson, AIA, and Patrick Cooke, AIA, Thomson & Cooke Architects. Contractor: Hyp Renovations. Tub, Plumbing Fixtures & Flooring: waterworks.com. Marble Backsplash & Counter: atlasstonefabricators.com. Tub Sconces: urbanelectric.com. Mirror: mirrorlot.com. Vanity Sconces: circalighting.com. Vanity: sinklegs.com through weaverhardware.com. Rug: districtloom.com.