Design know-how and fast food generally go together about as well as a vegan and a cheeseburger. What often passes for McDécor—garish plastic furniture, hospital-strength fluorescent lights, beige-tiled floors—could defeat even the strongest appetite. Surely, a critic of fast-food culture might point out, there's a correlation between the artificial, processed atmosphere of these restaurants and the artificial, processed meals they serve.

In 1993, restauranteur Steve Ells decided to turn this inference on its head and create a dining space that reflected the output of his own kitchen: simple but high-quality ingredients, combined in unexpected ways. Ells converted an old ice-cream parlor near the campus of Denver University into a burrito joint, Chipotle Mexican Grill. It proved such an immediate success that Ells opened a second location—and this time, he brought in an architect to help design it.

Ells turned to his friend, the prophetically named Brand Gould, who'd just left a big architecture firm in Denver. Together they developed what has become Chipotle's signature store design, a concept that weds industrial materials (corrugated metal, stainless steel, schedule-40 plumbing pipes) to birch wood and chili-red accents for a warmed-up factory look.

Chipotle, still headed by Ells as chairman and CEO, now has 580 stores around the country that rang up nearly $830 million in revenue last year. (The growth was fueled by McDonald's Corp., which had a controlling interest in the company from 2001 to 2006.) But the original palette of materials remains more or less unchanged, as does the initial decision not to restrict designers to prescribed floor plans.

“[Ells] wanted the food and the architecture to parallel each other,” explains Chipotle's current director of design, Scott Shippey, who joined the company in 1997 as it prepared to open its ninth store. “Our food is simple ingredients—it's what you do with them [that counts]. The idea with the architecture was, let's take these simple, rudimentary materials, but what we do with them will say something, and we'll get a look out of that.”

Shippey, who has a bachelor's in environmental design from Texas A&M, is based in Austin, Texas, and remotely supervises a team of three architects—known as design managers, or DMs—at the company's Denver headquarters. Each architect handles a different region. Chipotle also employs about a dozen construction managers, who work closely with local contractors.

Shippey's team handled all store design internally until about a year and a half ago, when the company's breakneck growth—it opened 94 stores in 2006 alone— spurred them to form partnerships with small and midsize firms in areas where they didn't have much local experience. Today the DMs design stores only “when we have tricky spaces, like in Manhattan, or if it's a real flagship. It's almost like a perk now,” he says.

The company maintains a website with standards that tell outside architects and contractors how to trim out the stainless steel, for instance, or to use tankless water heaters for energy savings. And the DMs keep an eye on each new design as it develops. “We review all schematic design before we cut any of our outside architects loose,” says Shippey.

Chipotle's architectural flexibility means that the company can enter different kinds of spaces—tight urban infill or freestanding suburban box—and tailor the design to fit, while still imprinting the store with the unmistakable brand conferred by its materials.

Store interiors, which average 2,200 square feet, can vary widely, but all Chipotle outlets share an intuitive layout free of the usual fast-food signage, which Shippey likens to “fingernails on a chalkboard.” “You don't need a lot of this busy signage to say: Stand here, order here, leave here,” he says. “The way you lay out a store can very easily guide [customers].”

Transparency is another guiding principle. In his first Denver-area Chipotles, Ells wanted customers to be able to see cooks chopping vegetables and grilling chicken, so an open kitchen was essential. As the company rolls out 95 to 100 new stores over the next year, Shippey says, he will try to make the kitchens more transparent, “to put the functionality of cooking on display.” Even after 10 years with the company and hundreds of store openings, he's excited about it.

“The stores are still just awesome,” Shippey says. “They're cool. I hate to sound like a juvenile about it—but they're cool.”