Situated at the confluence of the Altmühl and Danube rivers, Kelheim — a Bavarian town with narrow lanes and medieval buildings — is famed for a Benedictine monastery founded in 650 and the elegantly neoclassical Befreiungshalle (Hall of Liberation) perched atop a mound overlooking the 15,000-inhabitant town. Most river-cruise ships don’t sail directly to Kelheim but offer day trips to the region from Regensburg.