Three rivers converge at Passau, as do bright young minds who have descended on this university town for centuries. You’ll get your own crash course in local history while exploring the cobblestoned old town (Altstadt) on Crystal Cruises’ complimentary guided tour. Highlights include the Gothic town hall (Altes Rathaus), featuring 19th-century murals, and St. Stephen Cathedral, with its truly impressive pipe organ. From the fortress above the city, the Veste Oberhaus, you’ll admire views extending all the way to the Black Forest. The Treasures of the Danube itinerary enables you to spend the night in Passau, giving you extra time to enjoy its riverside bike path and ample people-watching and beer-drinking opportunities.