Marcus Aurelius had the legionary fortress of Castra Regina built here, on the northernmost bend of the Danube, and its north gate, the Porta Praetoria, still stands in Regensburg's old town, built into later buildings, with a foundation inscription dated to AD 179. Outside the fortress walls, the canabae, the civilian settlements where traders, craftsmen and soldiers' families lived, spread along the river, and the eastern canabae are a piece of the World Heritage property for the Danube Limes. Regensburg's medieval old town, built on top of the Roman city, has its own UNESCO listing.
Regensburg is one of the best-preserved medieval cities in Germany, with towers built by rich merchant families, a Gothic cathedral and a maze of narrow streets. The Stone Bridge, built in the twelfth century, crosses the Danube on sixteen arches and was a marvel of its time. Next to it, the Historische Wurstkuchl, a small sausage kitchen, has been serving grilled sausages with sauerkraut and sweet mustard for centuries. A short ride downstream, the Walhalla, a neoclassical temple built by Ludwig I of Bavaria to honour great Germans, stands on a hill above the river at Donaustauf.
The riding is enjoyable. The roads along the Danube are flat and scenic, and to the north, the Bavarian Forest offers twisty roads through hills and forests. The Altmühl valley to the west has limestone cliffs and gentle curves. The old town of Regensburg is mostly pedestrian, with cobbles, and parking for motorcycles is limited, so it is best to park outside and walk. Traffic around the city can be heavy. Weather is continental, with hot summers and cold winters, and fog along the river in autumn.
Regensburg has filling stations, supermarkets and inns. Bavarian food is hearty: sausages, pork knuckle, dumplings and beer from the local breweries. The city has a lively student life and many cafés. Walk through the old town to the Porta Praetoria, run your hand along the Roman stones, then cross the Stone Bridge and buy a sausage at the Wurstkuchl; it is the same view of the river and the cathedral that travellers have enjoyed for eight hundred years.