In 2009, Juicy Couture velour sweatsuits and low-rise jeans reigned supreme in the world of fashion. That same year, the renowned architecture firm Lake Flato completed a modernist masterpiece in North Scottsdale, Arizona. These days, athleisure has continued to evolve and high-waisted jeans have moved to the forefront; the house, on the other hand, has achieved near-icon status. Nestled into its steep site, it frames views of the surrounding Sonoran Desert and preserves its inhabitants’ privacy. Constructed of weathered steel and stucco, it unfolds as a series of pavilions shaded by generous overhangs and opens to the landscape via pivot doors.

Interior designer David Michael Miller had known of the house before its new owner engaged him to update the interiors, and he welcomed the opportunity to bring richness and depth to its spaces. His efforts would be concentrated on the furnishings and art (his client came equipped with a standout collection) rather than making big changes. “The overarching logic was that this was an amazing piece of architecture, and we didn’t want to do anything to hurt it,” he explains. “A lot of the parts and pieces are unique and bespoke. Lake Flato has rigorous discipline. Their work is good forever.”

Aesthetically, Miller and his client “were aligned from the get-go, so it was effortless,” says the designer. Both have an affinity for Christopher Farr rugs and furniture by B&B Italia and Liaigre, and that shared language informed Miller’s vision. After some back-and-forth, the two settled on a mix that’s comfortable and stylish yet restrained. “We didn’t want the house to feel full, but to have things that could hold their own in the space,” the designer says. He opted for a tailored B&B Italia sectional for the living room with an equally tailored leather-wrapped Liaigre ottoman. Behind the sectional is another Liaigre piece—a console of Macassar ebony and black lacquer. “I love the slickness of it,” remarks Miller. He furnished the adjacent dining area with a warm walnut dining table, surrounding it with leather-encased chairs. For the lighting, Miller favored bigger, more gestural pieces with mass, such as the Jonathan Browning fixture over the dining table—a linear cluster of blackened bronze pyramids—and the Liaigre fixture above the kitchen island.

The designer took a similar tack with the outdoor furnishings. “We didn’t want things to be too ‘notice me,’” he says. “We wanted things that were significant, but they also had to fit in so they didn’t compete with the view.” A collection of pieces in anodized aluminum and woven resin proved ideal, offering comfort along with a low-key profile. Miller also worked in a collection of vintage midcentury David Cressey planters, noting, “This is the perfect house for them.”

After nearly a decade, the home did require a few changes here and there. Most were minor, such as relocating a few TVs. And a couple of built-ins were swapped out, like the headboard in the master bedroom and a shallow table in the foyer. Miller moved the latter to storage in case future residents want to resurrect it, having learned from history. “In those Frank Lloyd Wright houses, later generations changed things, and you can’t change them back,” he says. In the table’s place is a more commanding cabinet in lacquer and rift walnut that relates to finishes elsewhere. Miller’s biggest move happened in the nearby powder room, where he started from scratch, adding a new stone tablet to the back wall, a custom vanity cabinet and a stone bowl sink, new plumbing fixtures and an Alison Berger light. “We made it richer and more consistent in concept with the rest of the house,” he reports. “It’s a special moment.”

For Miller, the opportunity to work on this house was a welcome change of pace. “Most of our work is new construction, so it was fun to step into a building that was so rigorous in its design that all it needed was the right furnishings treatment.” And it helped that he and his client were so closely in step with each other’s aesthetic. “When it’s right, it’s right,” says the designer. “Then it’s not work. It’s perfect.” Also pleased are the home’s original architects. Miller reports, “They came back to me and said they loved the interiors.”