Seville, the landlocked capital of Andalusia, is a real test of whether a surge of modern building can sit well in a city with a fragile, storied past. I was last there a year before it staged the 1992 World Expo, and worried in a grumpy way that it might be too hell-bent in pursuit of the new. (The urge for renewal is more easily understood when you discover that, thanks to Franco, as late as 1982, Andalusia had not one functioning theater or orchestra.) As it worked out, the Expo left three notable landmarks: the Alamillo Bridge, by Santiago Calatrava, supported by its single, sharply angled pylon like the upended frame of a harp; the Santa Justa railroad station, a truly inspired updating of the Victorian vaulted shed, by Antonio Cruz and Antonio Ortiz; and an airport terminal by Rafael Moneo that, to this day, is a pleasure to pass through. None of these damaged the city's character.

The old core of Seville was shaped by the Arabs from 710 to 1248; Moorish architecture went with what was, by the tenth century, city planning of a very advanced order. Simple and effective climate control, conceived in the desert, came to urban living in the form of many inner courtyards where fountains were used to convect warm air upward and cool air downward for human comfort. You could have hoped that the Arab street plan, with as many twists as a souk, would defeat the car. But by 1991, I could already see that the local drivers had an insouciance able to make the most formidable obstructions seem malleable. And by the beginning of this century, cars were infesting every alley.

Seville was already a thriving urban center when Caesar arrived in 45 b.c. "You can't dig anywhere in this city and not find something old," said Emilio Carrillo, the deputy mayor whose remit is to shape Seville's future without further harming its extensive past, a trick that European planners never find easy. We spoke in an airless office on an island in the middle of the Guadalquivir River, a relic of the Expo site. Carrillo knows what is at stake—he's also a professor of history, as comfortable with Roman chronicles as with the grand urban scheme that he now directs, funded to the tune of four billion dollars.

When we met, he had a big victory behind him. Seventy-six percent of the citizens had voted for a new plan that would, in effect, remove cars from a large part of the old city. On one condition: that a new tramway would circle the city core to make pedestrian access much easier—as historic centers go, Seville's is enormous, three square miles. The tramway, built in a year, will be a boon not simply to the more than 700,000 residents of Seville but also to the 2.2 million visitors who come each year—as will the forty new hotels planned (many converted from convents). A high-speed rail line already brings Seville within two and a half hours of Madrid, and a new line is being built from the city to the Mediterranean playground of Malaga, ninety miles away—a journey that will take just over an hour instead of three.