Passau sits where three rivers meet, the Danube, the Inn and the Ilz, and from the high point of the Oberhaus fortress you can see their colours run side by side before mixing: green from the Inn, blue-grey from the Danube, and dark from the Ilz, which flows down from the Bavarian Forest stained by peat. The Romans knew this spot well. They had a fort here called Batavis, named after a unit of Batavian soldiers from the Rhine delta, and another at Boiotro across the Inn, and along the Danube downstream they built small fortified towers called burgi to watch the river and signal to each other. One of these late Roman burgi stood near Haibach, and its remains are part of the Danube Limes, inscribed by UNESCO in 2021 as part of the Frontiers of the Roman Empire.
The Danube was the frontier of the empire in this region for four centuries, and the burgi of the late period, in the fourth century, reflected a more defensive posture, as pressure from Germanic peoples increased. Today the river flows peacefully past wooded slopes, with cruise boats, cyclists on the Danube cycle path, and fishermen on the banks. Passau itself, with its baroque cathedral and one of the world's largest church organs, is a lively university town.
Riding along the Danube east of Passau is a joy. The roads on both banks follow the river through a narrow, wooded valley, with gentle curves and views of the water, and lead toward Austria and the Schlögen loop, where the river makes a dramatic hairpin through the hills. North of Passau, the Bavarian Forest offers more challenging riding, with climbs, tight bends and dense woods. Traffic in the valley can be busy in summer, and cyclists are everywhere on the riverside paths and lanes, so stay alert.
Passau, about five kilometres away, is a town of around fifty thousand people with fuel, cafés, beer gardens and restaurants, and Salzweg, just north, is another option. Try Bavarian dishes such as roast pork with dumplings, or fresh fish from the river. Stop by the river near Haibach, look at the flowing water, and think of the Roman soldiers who watched over it, peering across at the dark forests on the far bank. Then ride into Passau and climb up to the fortress for the view of the three rivers.