At the time, the couple’s house hunt seemed doomed to fail anyway, and they paused to reconsider their situation. In 2001, recently married and living in San Francisco, Tony and Rachel had decided they wanted to buy a modern house. Because they like to hike and ride mountain bikes, their search led to leafy, hilly Mill Valley, a 20-minute drive north across the Golden Gate Bridge. But this genteel Marin County enclave is steeped in a rootsy tradition that wasn’t necessarily hospitable to modern design. The Arts and Crafts style seemed to hold pride of place. “We wanted to buy something modern,” Rachel says, “and we just weren’t finding anything.” So they took a deep breath and sprung for the concrete colossus.

The Shermans then began searching for an architect in sync with their unusual dilemma: how to build a light, modern house of 4,000 square feet on a platform meant for a house more than twice that size. Fortuitously, they happened to read about Lorcan O’Herlihy. The Los Angeles architect had just completed a svelte, airy house on a hefty hillside foundation decreed by L.A.’s tough new earthquake code requirements. O’Herlihy also seemed to appreciate the warm side of modernism, which the couple preferred. “We called him right away, and he came up to see us the next week,” Tony says.

“Tony and Rachel were excited about the prospect of having a modern house,” O’Herlihy recalls. “But Mill Valley’s design-review board is very strict—they weren’t known for embracing contemporary architecture.”

As the Shermans learned, to their chagrin, they’d be facing yet another dilemma: how to convince the tradition-minded civic authorities to approve a modern house in a highly visible hillside location. O’Herlihy’s solution seems simple in retrospect. “I knew I had to stay true to the indigenous environment,” he explains. “I had to tie the house to the existing geography, its spiraling movements and folding planes, and to the spectacular view. I also decided to use Mill Valley’s traditional material—wood—but to use it in an untraditional way.”

According to Tony, “The first sketches looked like a spaceship, and I said, ‘Oh boy, that doesn’t even look like a house.’” A few months later, the couple saw a more refined model. “This one was brilliant,” he says, “and it’s essentially what we live in now.”

Like a natural outcropping, the house follows the folding, bending contours of the hill. Its 4,000 square feet are stacked on two levels resembling long angled bars, with the upper layer offset to one side and cantilevered over the precipitous hill toward the view. The lower volume is wrapped in a floating cedar skin and the top is covered in smooth troweled plaster, mimicking the hillside in color and texture (at least in summer) as well as form. O’Herlihy’s strategy was a success: The board approved the house without a single dissenting vote.

On Christmas Eve 2004, with a sigh of relief, Tony and Rachel and their newborn daughter moved in. “Living here is different from anywhere I’ve ever been,” says Rachel, who grew up in a traditional house in Poughkeepsie, New York. “It’s light and open with big windows framing our views. There’s lots of wood—mahogany window frames, floors and furnishings Lorcan designed—so it’s a modern house that always seems warm, never cold.” She continues, “At night, the house really shines. The angles rise, you see the stars—the bay lights twinkling—and it feels like we’re living outside.”