For nearly two centuries, one of the most powerful families in Europe lived in what had been a monastery in Regensburg. The Thurn und Taxis family ran the imperial postal service of the Holy Roman Empire, and when the Imperial Diet settled in the city in the seventeenth century, the family came too. In 1812 they acquired the abbey of St Emmeram and turned it into a palace, and it is still the home of the family today, a vast complex of cloisters, ballrooms and gardens beside the old town.
The Roman story lies just beneath the surface. St Emmeram stands near the line of the Roman camp, and the area around it was a cemetery and settlement in antiquity, then an early Christian burial place. The abbey church is one of the finest in Bavaria, with an interior of exuberant baroque decoration by the Asam brothers, who covered the walls with gilded stucco. The crypt is far older, and holds the tomb of Saint Emmeram, a missionary bishop who died in the seventh century.
The old town around the palace is a pleasure to wander, with its tall merchants' houses, the stone bridge, the cathedral and a lot of cafes and bookshops. The Danube Limes and the old town are both UNESCO World Heritage sites. Bikes are best left on the edge, since the central lanes are cobbled and often closed to cars, and the city has plenty of parking near the ring road.
Regensburg has about a hundred and thirty thousand people, so you will find fuel, food and repairs without trouble, and Reinhausen, just over the water, has its own small centre. Beer is excellent, and the Christmas market in the palace courtyard, held in the weeks before Christmas, is one of the most famous in Germany. If you visit in summer, there are open-air concerts. Spring and autumn give you the best light. A ride out of the city to the north leads into rolling Upper Palatinate country, quiet and green.