"In terms of culture, Spain is the most interesting country in Europe at the moment," he said, sipping an espresso as dense as tar as we talked in his London offices, which sit on the banks of the Thames. "The craftsmanship is as good as the best anywhere."

From the Pompidou Center in Paris to the Lloyds Building in London, there's always been a strong utopian theme in Rogers's public buildings, a fresh wind of openness and transparency. And like many of us, he felt that airports had become places to loathe rather than love, and a suitable target for vigorous deconstruction. At Barajas he got the chance to do just that.

To use a British term of visceral approbation, I was gob-smacked when I flew in from London. In a sense, Barajas is already airborne. It sits on a plateau two thousand feet above sea level, and this altitude, along with the pale hills that surround the airport, produces a light of sharp brilliance.

Terminal 4, the core of Barajas, is more than five million square feet in area. There are three levels aboveground and three below. Rogers wanted daylight from the roof to flood the top three floors. He did this by creating what he calls canyons—uninterrupted breaks in the structure from roof to ground level. Across the canyons, bridges connect the areas used for check-in, security, and boarding. "I wanted to get the spirit of travel back, the romance of those wonderful, lofty railway stations where you would set off for places like Istanbul," Rogers told me. "That was part of the concept of a large roof—most of all, we wanted to get the light in."

What made the most impact, though, as I moved happily through this vastness, was the novelty of the roof itself, which undulates like an arrested wave and is finished with planks of bamboo. Few people know, however, that the bamboo nearly had to be abandoned. Trial samples failed fireproofing tests. Only when a German fabricator found a way to laminate bamboo like plywood, using a flame-suppressing glue, was it cleared for use. Now, light filters between the bamboo planks and is focused through large portholes, suffusing everything in the space with a sort of weightlessness.

Barajas was completed within six years of being conceived. "Arguably," said Rogers, "in the way it was run and delivered, the most exciting job of my life." The architect, who was born in Italy, is a devoted foodie—his wife, Ruth, created the swish River Café (and wrote the cookbooks featuring its refined Italian cuisine), which is conveniently next to his offices. "I'm a great believer in food as a good way of sparking ideas. In Spain we ate very well, we drank, we went out at night, but they get the work done."

In contrast, his new British Airways Terminal 5 at Heathrow, which opens this spring, took twenty years to build. What architects call the "client body" was 450 people strong in London, every one of them with an opinion; in Madrid, it was 20.