PASSAU, a town and episcopal see of Germany, in the prov ince of Lower Bavaria, at the confluence of the Danube, the Inn and the Ilz, close to the Austrian frontier, 89 m. N.E. from Munich and 74 S.E. of Regensburg by rail. Pop. (1933) 25,181, nearly all being Roman Catholics. On the site of the present Innstadt there was a pre-Roman settlement, Boiudurum. Afterwards the Romans established a colony of Batavian veterans, the castra batava here. It received civic rights in 1225. The bishopric was founded by St. Boniface in 738 and included until 1468 not only much of Bavaria, but practically the whole of the archduchy of Austria. About 1260 the bishop became a prince of the empire. In 1803 the bishopric was secularized, and in 18o5 its lands came into the possession of Bavaria. The area, which was diminished in the 15th, and again in the 18th century, was then about 35o sq.m., and the population about 5o,000. A new bishopric of Passau, with ecclesiastical jurisdiction only, was established in 1817.
Passau consists of the town proper, lying on the rocky tongue of land between the Danube and the Inn, and of suburbs, lying along the other rivers. Of the II churches, the most interesting is the cathedral of St. Stephen. The two linked fortresses, the Oberhaus and the Niederhaus, are the remains of the fortifications. The former was built early in the 13th century by the bishop in consequence of a revolt on the part of the citizens ; the latter is mentioned as early as 737. The chief industries are the manufacture of tobacco, beer, leather, porcelain, machinery, paper, iron founding and the quarrying of graphite and granite. Large quantities of timber are floated down the Ilz. Passau is a tourist centre, and has an important river trade, especially since the construction of the Rhine-Main-Danube canal.
See W . M. Schmidt, Gesch. der Stadt Passau (1928).