Viewed from a vantage point just across the Danube, Regensburg has changed surprisingly little since Emperor Maximilian's visit nearly five centuries ago. More than 1,300 medieval buildings pack an Old City barely a half-mile square.

"Regensburg surpasses every German city with its outstanding and vast buildings."Emperor Maximilian I, 1517

Viewed from a vantage point just across the Danube, Regensburg has changed surprisingly little since Emperor Maximilian's visit nearly five centuries ago. More than 1,300 medieval buildings pack an Old City barely a half-mile square. Thanks to the city's dual role as an ancient and medieval religious center and trading crossroads, church spires share the skyscape with the Italianate towers of merchant homes.

The buildings are remarkably intact. Allied bombs touched only the southern fringe of the city. And its relative prosperity during the Middle Ages was followed by centuries of decline, when the city couldn't afford to tear down or build. Call it "preservation through poverty." At the same time, the impoverished city was of no interest to wars that ravaged nearby cities. In fact, most buildings were untouched until recent - and thoughtful - restoration.

But Regensburg is no museum city. In the early 1950s, city leaders decreed that commercial use would be confined to the first two floors of any historic building. (And tax breaks are given to owners who open their buildings' courtyards to foot traffic.) More than 14,000 residents live in the upper floors.

In 1965, the University of Regensburg was founded; today, many of the area's 20,000 students make their homes downtown alongside thousands of Baby Boomers who were once urban pioneers. The concentration of downtown residents, combined with a lively student presence and the prosperity of nearby high-tech giants, has created a livable, upscale environment. Its cultural and culinary offerings - and a clubby nightlife - exceed expectation in a city of barely 140,000 residents.

Despite all this, tourism has just recently arrived in Regensburg, perhaps due to the attraction of nearby Nuremberg, Munich and Rothenburg - each about an hour's drive away. Still, the city has been gearing up for visitors for years, giving today's guests the best of both worlds: a strong tourism infrastructure without an overwhelming tourist presence.

Regensburg was established around 500 BC as Radasbona, a Celtic settlement. In 179 AD, the Romans established a garrison there to guard the Empire's frontier at the Danube's northernmost point. Like other Roman camps, Castra Regina was laid out in a rectangular shape with two main crossing streets. Viewing a map, visitors can easily discern the outline of the ancient city. On foot, they can still walk the perimeter of original Roman garrison and in places see the remains of its walls.

The city became a bishopric in 739, and its many churches and monasteries strengthened Regensburg's role as a center of Christianity. By the tenth century, the city bulged beyond its walls, and fortifications were built outside the main camp. In 1135, the city started construction on a thousand-foot stone bridge, one of few across the Danube - and an architectural marvel that still stands. By the time it was finished 11 years later, Regensburg had become a major trade center and a crossroads for mercantile traffic heading to and from Italy and as far east as Kiev. In 1245, Regensburg was proclaimed a Free Imperial City, setting the stage for three centuries of prosperity and prosperity.

With their growing wealth, Regensburg's merchants built elaborate patrician homes in the form of Italian fortified fortresses. Each showed off his wealth and prestige by trying to build the highest tower. Nineteen still stand today. During this period, the city's faithful built the Gothic St. Peter's Cathedral (a 250-year undertaking) and a multitude of churches and monasteries.

Prosperity came to an end when Bavarian dukes brought taxation to Regensburg and it was a free city no longer. Regensburg moved quickly from rich to poor. Since there wasn't enough money to build anew, old buildings were maintained rather than demolished. Preservation through poverty.

It's not difficult to lose oneself in the city's history - or even move through it. Streets still mark the rectangular shape of the Roman camp. Along the northern perimeter, the fortified wall of the Porta Praetoria, once a watchtower, still stands guard. Along the western side, the Bachgasse winds over the former streambed that paralleled the garrison wall (and emptied the camp's effluent). All that remains of the medieval wall, however, is the 14th-century East Gate. The remaining walls were torn down and replaced by a ring of gardens and greenspace that embrace the city.