This popular river cruise stop sits at the German-Austrian border and is the last major German city on the Danube before entering Austria. Passau sits on the confluence of the Danube, the Inn and the Ilz, so it is fitting that it is known as “the Dreiflüssestadt”, which means the “City of Three Rivers.” The historical center offers a cathedral, churches and museums to explore, and the embankment is perfect for a romantic stroll. For those looking to get the blood pumping, there is a cycling path from Passau all the way to Vienna.