Three years ago, though, the city tore up the pavement and found the Cheonggyecheon still flowing below. Last October, the restored waterway was opened to the public, and the steel and concrete of downtown Seoul was transformed through its quiet presence, in the same way that Manhattan is softened by Central Park. Along one stretch, three columns from the old expressway were left standing, reminders of the costs of headlong modernization.

Seoul has been the capital of Korea—an ancient culture founded more than four thousand years ago—since the beginning of the Chosun dynasty in 1394. The country flourished under the Chosun rulers, whose era lasted until 1910. That year, Korea became a colony of Japan, a humiliation that ended with Japan's defeat in World War II but that is still the cause of much anger today.

Although Seoul has sprawled in all directions over the last few decades—some 10.3 million people live here, one-fifth of the country's population—its epicenter has not shifted since the 1300s. In downtown Seoul, centuries-old palaces and traditional markets sit alongside government offices and gleaming skyscrapers, making for sometimes jarring juxtapositions of the ancient and the futuristic. The city's twenty-five wards fan out from downtown and are now roughly divided between those south of the nearly half-mile-wide Han River and those north of it. The wild growth of the last generation took place mostly south of the river; the areas north of Seoul—the city is less than forty miles south of the demilitarized zone that has divided the Korean peninsula for half a century—grew more slowly, mostly because of the Cold War with North Korea. (Korea was divided in 1945, when America assumed stewardship of the southern half and the Soviet Union of the northern, a temporary proposal that became permanent in 1950 when North Korean troops marched across the thirty-eighth parallel, sparking the Korean War.)

And yet despite the first-world amenities and even sophistication of Seoul—the clean, crime-free streets; the public art; the brisk energy—Americans have never considered it an essential Asian destination. It may be more efficient than Beijing and more manageable than Tokyo, but when Americans think of Seoul, they think of the impoverished, war-torn Korea of M*A*S*H, or, lately, of North Korea, whose recent nuclear ambitions have agitated everyone but the South Koreans themselves.

Although the two countries have never officially reconciled, the South Koreans' attitude toward their estranged neighbor has changed dramatically in recent years. North Korean outbursts once sent South Koreans scurrying to their nearest supermarket to stock up on essentials, but no longer. In 2000, the two Koreas began a rapid process of rapprochement, and although South and North are far from reunification, young South Koreans now believe that the North's missiles are meant not for them but for their perceived enemies in the United States and Japan.