Passau is a city in Lower Bavaria, Germany, also known as the Dreiflüssestadt ("City of Three Rivers") because the Danube is joined there by the Inn from the south and the Ilz from the north.

Passau's population is 50,000, of whom about 12,000 are students at the University of Passau, renowned in Germany for its institutes of economics, law, theology, computer science and cultural studies.

Many river cruises down the Danube start at Passau and there is a cycling path all the way down to Vienna. It is on the designated heritage route, the Route of Emperors and Kings.

Passau is notable for its gothic and baroque architecture. The city is dominated by the Veste Oberhaus and the Veste Niederhaus, both parts of the former fortress of the Bishop, on the mountain crest between the Danube and the Ilz.

Tourism in Passau focuses mainly on the three rivers, the St. Stephen's Cathedral (Der Passauer Stephansdom) and the "Old City" (Die Altstadt).

With 17,774 pipes and 233 registers, the organ at St. Stephen's was long held to be the largest church pipe organ in the world and is today second in size only to the organ at First Congregational Church of Los Angeles, which was expanded in 1994. Organ concerts are held daily between May and September. St.Stephen's is a true masterpiece of Italian Baroque, built by Italian architect Carlo Lurago and decorated in part by Carpoforo Tencalla.

Among many other churches are the Jesuits church of St. Michael, the oldest parish church of St. Paul and the pilgrim church Mariahilf on the hill south of the rivers Inn and Danube.

Before the cathedral is a large square (Domplatz) with the Lamberg-Palais, where the Peace of Passau was concluded. The medieval Old Residence south of the cathedral and the baroque New Residence further west at Residenzplatz were the palaces of the Prince-Bishops within the city. Right beside the 14th century Gothic city hall with its neo Gothic tower and the big 19th century former Hauptzollamtsgebaude (Main Customs Office) at the Danube is the Scharfrichterhaus, an important jazz and cabaret stage on which political cabaret is performed.