To be privately owned
Niederhaus Castle

In Passau, Veste Niederhaus is situated on a rocky promontory at the confluence of the Ilz and Danube rivers. Located below the Veste Oberhaus, it has shaped the cityscape for centuries.
History+
The origins of settlement on the promontory date back to 737, when Duke Odilo of Bavaria established a temporary residence there for Bishop Vivilo and refugee nuns. The hilltop castle already existed around 1250, as old building accounts distinguished between an “old” and “new” part of the castle. From the mid-14th century, the names “Oberhaus” and “Niederhaus” became common. In 1358, a room for 13 pilgrims was created in the large cellar vault, today known as the Pilgrimskeller. Following the capture of Niederhaus by Passau citizens in a conflict against the bishop, a double battlement connecting it to Veste Oberhaus was built in 1367. A gunpowder explosion destroyed the castle in 1435, but reconstruction took place under Prince-Bishop Leonhard von Laiming, completed by 1444 at the latest. At this time, Niederhaus, with its halls, a knight's hall, and two castle chapels, served as a secondary residence for the bishops. In the 17th century, the castle was converted into a prison for unruly clerics, and in 1762, under Prince-Bishop Joseph von Thun, it became a workhouse and penitentiary.
Source: Wikipedia · Licence: CC BY-SA 4.0
This description draws on the facts documented in the linked Wikipedia article; Wikipedia content is licensed under CC BY-SA 4.0. Wording and editing: Mobile History.
Location: 48.5756, 13.4744