To be privately owned
Wolfenburg Castle (Kelsterbach)

Wolfenburg Castle, also known as Kelsterbach Castle, was once a Renaissance structure in the Hessian town of Kelsterbach. With its distinctive four corner towers, it once shaped the landscape north of the village near the banks of the Main River.
History+
Count Wolfgang von Isenburg, the then owner of Kelsterbach, had the Wolfenburg built between 1564 and 1580 in the Renaissance style. He commissioned Georg Rubin as the master builder for this project. In 1639, during the Thirty Years' War, the castle suffered looting and damage. The high costs of reconstruction led to the building being left to decay.
Source: Wikipedia · Licence: CC BY-SA 4.0 · Image: Matthäus Merian / Public domain via Wikimedia Commons
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: 50.0706, 8.5307