Johannes Kepler died in Regensburg in November 1630, nearly penniless, having ridden here to try to collect money the emperor owed him. He is one of the great figures of European science, the man who worked out that planets move in ellipses, and his death in this city is a reminder of how much the town meant in his time. He was buried in the cemetery of St Peter, but the grave was lost when the cemetery was destroyed during the Thirty Years War. A memorial temple stands in a park by the old town, and the small house where he spent his last days is now a museum.
Regensburg had a long run as an imperial city. From 1663 to 1806, the Perpetual Imperial Diet, the parliament of the Holy Roman Empire, met in the old town hall, and the city filled with diplomats, courtiers and servants. The meeting room, the Imperial Hall, can still be visited, along with the old interrogation chambers beneath it. The whole assembly was a slow, ceremonial machine, and the city's streets and inns bear traces of it.
The old fortress of Castra Regina lay under all this. The Roman soldiers who built it in 179 are now far behind the layers of Kepler and the emperors, but their street grid is still there. The Danube Limes, of which it was a part, was listed by UNESCO in 2021, along with the old town in 2006.
If you arrive on a motorcycle, the ring roads lead easily to the old town, where you can park near the edge and walk. Regensburg has about a hundred and thirty thousand people, so fuel and food are plentiful. The Danube is the central feature, with the stone bridge and the island district of Stadtamhof, now a pleasant place for cafes. Take your time to look at the Imperial Hall, then sit by the river with a drink and think about the long chain of people who passed this way. Spring and autumn are the best seasons.