Passau (anc. Batava Castro), a town of Bavaria, at the confluence of the Inn and the Danube, 92 m. E. N. E. of Munich; pop. in 1871, 13,389. It is divided by the rivers into three parts, the central one being the town proper, and the others, Innstadt on the Inn, and Ilzstadt on the Danube, being suburbs. The Ilz, a tributary of the Danube, flows between Ilzstadt and Anger. Two castles and eight smaller works of defence constitute Pas-sau one of the most important strongholds on the Danube. It has a cathedral, a public library, a theatre, an old abbey, a bronze statue of King Maximilian Joseph, several schools and hospitals, a lunatic asylum, manufactories of porcelain, leather, tobacco, beer, paper, iron, and copper, and an active trade on the Danube. Its bishops were formerly independent princes, but it was secularized in 1803, and incorporated with Bavaria in 1805. In 1552 a treaty guaranteeing religious freedom to the German Protestants was concluded here between the emperor Charles V. and Maurice of Saxony.