Weißenburg in Bayern is the best Roman stop in this part of Franconia, and the fort here, known in antiquity as Biriciana, was a serious place. It stood on the Upper German-Raetian Limes, which UNESCO listed in 2005, and it held a cavalry unit at its height. Today you can walk the reconstructed gate and walls and then visit the Roman baths, which are among the best preserved in southern Germany and sit under a modern roof beside the old town. In 1979, builders found a hoard of bronze and silver objects buried in the fort's grounds, the Weißenburg treasure, which includes ceremonial armour, and it is now one of the key finds of Roman Bavaria.
The town itself is a pleasant surprise, a walled medieval town of seventeen thousand people with towers, half-timbered houses and a main street of cafes and bakeries. Above it stands the Wülzburg, a massive Renaissance fortress that later served as a prison. Weißenburg also has a long tradition of brewing and a local appetite for pork and dumplings, in the Franconian way. Fuel and supermarkets are easy to find, and parking near the old town is straightforward for bikes.
The riding around here is gentle and varied. The Altmühl Valley Nature Park lies just south, with limestone cliffs, river meanders and long smooth curves, and to the north the Franconian Lake District offers flat, quick roads between reservoirs and farmland. Ellingen, a short run away, has a baroque palace of the Teutonic Order in a very tidy small town. Roads are well surfaced and traffic is moderate, though weekends in good weather bring plenty of cyclists and day trippers.
For the stop, spend time at the baths first, because they make the Romans real, then climb the street to the old town for coffee. If the day is hot, the shade of the medieval gates is welcome. Spring and early autumn are the best seasons, with the fields in bloom or golden. After a morning here, you will notice the Limes everywhere in the countryside, a long, quiet line that once marked the edge of an empire.