In 1957, Arthur Witthoefft was overseeing the construction of his new residence on four-plus acres in the Whippoorwill section of Armonk, New York, when a passerby dropped in. Witthoefft was an architect in the Manhattan office of corporate modernists Skidmore, Owings & Merrill, and his design was a lapidary example of Miesian simplicity: a 25-by-95-foot rectangle, composed of a black exposed-steel frame, front and northern elevations clad largely in white glazed brick, and southern and western exposures enclosed by floor-to-ceiling glass sliders. At the time, there was little development in semirural Whippoorwill other than a scattering of estates, and the design-forward creation, atop its lush sloping site, made an especially arresting impression. Which prompted the visitor’s question. “This guy came up and said, ‘Pardon me, sir, I don’t understand,’” recalls Witthoefft, now 91 and still in practice. “‘There’s no traffic out here. How will you get any business for the motel you’re building?’”

The “motel” went on to win an AIA First Honor Award in 1962 and, as hostility toward the style turned to veneration, its merits became apparent—particularly to the current residents, Todd Goddard and Andrew Mandolene, a real estate broker and a creative director, respectively. A few years ago, they were living in California modernist E. Stewart Williams’s 1957 Kenaston House, in Rancho Mirage, when they decided to move. They loved the West, but they loved mid-century architecture even more—and were prepared to relocate for it. Finding a house in the Los Angeles area equal to the Kenaston, a minor gem they’d impeccably restored, at an affordable price proved difficult. “So we decided to see what else was out there,” says Mandolene. “If there was something special, we would go for it.”

With cherchez le modernisme as their rallying cry, they investigated the towns around New York City and southern New England, home to some classic examples of the genre. Goddard, whose affection for mid-century real estate compelled him to specialize in it, used his broker’s skills to nose out promising properties. “That led us to this house,” Mandolene recalls. The pair flew out from Los Angeles to take a look and was captivated by the structure’s remarkable design. “Of all the houses we saw, this was the only one that left us speechless,” says Mandolene.

That took vision, for what the men beheld was a ruin—more Charles Addams than Charles Eames. In 1989, Witthoefft and his wife, Eleanor, an interior designer, sold their home and moved to Florida; the property went through a couple of owners, one of whom abandoned it for seven years. “If it had been a wood-frame house, it would have collapsed,” says Mandolene. The walls and substructure swarmed with mildew and black mold. Water streamed in through the lights in the ceilings, and the roof had partially fallen in. The cantilevers at either end of the house had settled, damaging the brick exterior; the frame and window mullions were rusted and warped. A previous owner, rather than replacing the imploded air vents in the cement slab, had installed radiators, chewing up the diminutive white ceramic tiles and ruining the visual impact of the glass.

Realizing that an inspection would be pointless, Goddard and Mandolene tracked down the architect in Sarasota, Florida, and asked if the wreck could be salvaged. “It wasn’t that far gone,” Witthoefft recalls telling them. “It was built on solid rock, and the welded steel frame wasn’t going anywhere.” Thus reassured, the men acquired the house for the land value—outmaneuvering several developers who planned to tear it down—and dove in.

That meant, explains Mandolene, “restoring it exactly like it was built.” When asked why, he looks nonplussed. “Why would we change something when 50-plus years later it functions beautifully and is part of the architect’s vision? We don’t want the house to look like every other house,” he says, “because it never did.”

Accordingly, they engaged Witthoefft as a consultant, a role the architect embraced: making several site visits, supplying the original plans, and designing a new second-story master suite (later deemed too expensive and unnecessary). The pair supplemented this with their own restoration chops. “We did tons of research ourselves and took the lead from Arthur on every detail,” Mandolene says. The architect was impressed: “It was surprising the way they just grabbed hold of the problem and solved it.”

In fact, solving the problem took two long years. Goddard and Mandolene had the mold removed and took up residence in July 2007. “That first day, we turned on the water, and each of us ran to the different places where it was squirting out of the walls,” Goddard recalls. Once they’d plugged the leaks, they camped out in the master suite, installing a refrigerator and a pair of burners, and lived and breathed the reconstruction. “Our contractor said it would be better to gut everything and get all the bad stuff out of the way,” Mandolene says. But the men were insistent upon saving as much of the original as possible, resulting in a mix of radical intervention, careful preservation, and everything in between.

With the exception of the front door and its adjacent glazing, all of the glass sliders and their frames were torn out and replaced. Large channels were jackhammered into the concrete floor slab—a snapshot shows the couple’s French bulldog posed stoically above the hallway excavation—and new HVAC vents, water pipes, and electrical conduits were installed. When their first contractor proved “good at gutting” but insufficiently meticulous, they replaced him with what Mandolene calls “a problem-solver.” Resourceful contractor number two reinforced the cracked concrete-block substructure above the cantilevers with strips of metal before applying new cement, and Goddard tracked down a glazed brick that matched the original to replace the damaged ones. “I was told it wasn’t available anymore, but I found a place in the Bronx that was using it on a commercial building,” he says.

Along with preserving some 75 percent of the structure, Goddard and Mandolene tried to replicate original materials and construction methods, such as in the repairs to the walls and ceiling. These were made of metal mesh lath covered in layers of hand-troweled plaster; using Sheetrock would have been easier and less expensive, but Goddard and Mandolene sought out craftspeople who could do it the old-fashioned way. “The ceiling was in horrible shape, and we had a guy leveling and smoothing for weeks,” Mandolene recalls. They also salvaged and reinstalled countless details, including light switches, door handles, socket plates, lighting fixtures, and fiberglass skylights—a strategy that imbues the house with a slightly unsettling quality, as though it had emerged, intact, from a time warp.

As their interior design scheme—in which nearly every piece is vintage, but nothing’s too precious to use—suggests, Goddard and Mandolene are at once curator precise and California casual, and this balance of meticulousness and ease remains evident in the minor changes they did decide to make.

After Eleanor Witthoefft, who had decorated the original, said she’d always found the floor tiles too small, the pair scored the restored slab with wide-set grid lines and added a glossy coat of pure-white resin. When I misidentify the accent color in the bar as turquoise, Mandolene politely corrects me. “It’s teal blue,” he says. “The architecture is sophisticated 1950s minimalism, and turquoise is 1950s kitsch. That’s not the definition of this house at all.”

To express the architecture’s strong rectilinear quality, the guest bath received rectilinear hardware and fixtures—including a square toilet. One change, however, is purely about delight: a fixed window in the master bath was replaced with a pivoting pane that, when open, brings the surrounding landscape indoors. (They also made two bedrooms into a study and expanded the garage to fit their collection of vintage autos.)

“It’s probably a little nutty,” Mandolene admits, reflecting on their insistence on pure preservation. And yet, he adds, “people think that this style of architecture doesn’t deserve to be landmarked because it’s not old enough, but it is part of architectural history, and it’s slowly disappearing.

Rancho Mirage let someone level Richard Neutra’s Maslon House—a masterpiece in mint condition. Unfortunately, developers pay, and they usually get what they want.”

Not this time. Thanks to Goddard and Mandolene’s passion and perfectionism, the bad guys lost, and the Witthoefft house stands stunningly resurrected. No one is more pleased than the man himself. “It made me so happy to see it so smart looking again,” the architect says. “They poured in a lot of love.”