Kumpfmühl is an ordinary southern suburb of Regensburg, with apartment blocks, a church and a quiet street grid, and under it lies one of the earliest Roman forts on the Danube. The fort, built in the first century, guarded a crossing of roads south of the river, and it was succeeded by the large legionary camp, Castra Regina, which gave the city its name after the late second century. A civil settlement, a vicus, grew beside the fort. Finds from it fill cases in the city's museums, and little shows above ground. The honest summary is that this is a stop for people who like their history thin and imaginative.
What Regensburg does offer a rider is a remarkable city, one of the best-preserved medieval centres in Germany, and a place where you can park the bike and walk for half a day. The old town sits where the Regen meets the Danube, with a twelfth-century Stone Bridge, a Gothic cathedral with twin spires, and narrow streets lined with tall tower houses that the old patrician families built to rival each other. A sausage kitchen beside the bridge claims to be among the oldest restaurants in the world, and you will smell it before you see it. UNESCO listed the old town in 2006.
The ride in from the south is not much to write about, since it is suburban streets, ring roads and traffic lights. If you are heading here from the Altmühl valley or the Bavarian Forest, the better moments come earlier, on the roads that climb over the Jura limestone ridges and descend into the Danube basin. Regensburg is a city of one hundred and thirty thousand, so fuel, parking and food are never an issue, though the centre is pedestrian and tight. Leave the bike at a garage or in one of the outer lots and walk in.
The Danube here is wide and calm, and cyclists run along its banks. A summer evening on the north bank in Stadtamhof, with beer and the old bridge lit, is a good reward for a day on the road. Early spring and autumn are best, because midsummer crowds fill every terrace and the centre is hot and dense. Kumpfmühl is the starting line, and the city is the finish.