Passau

Passau is a town in Lower Bavaria, Germany, known also as the Dreiflüssestadt, because the Danube is joined there by the Inn from the South, and the Ilz coming out of the Bavarian Forest to the North.

Trains regularly pass through Passau. The Hauptbahnhof is in the new city but buses run reguarly to the old city or you can walk in 15-20 mintues You can purchase a Bayern-Ticket which gives you unlimited travel in Bavaria on regional trains for a day.

Passau's city is spread out a little, but most places you will want to see are within walking distance. Buses are also common. You can walk 20 minutes from the city center and be in Austria.