To be privately owned
Bachem Castle

Bachem Castle, a former moated castle, is located in the Bachem district of Frechen in the Rhein-Erft-Kreis in North Rhine-Westphalia. Its special feature lies in its construction on wooden piles, similar to those in Venice, and the foundations of a residential tower, which date back to an early Roman aqueduct.
History+
The origins of Bachem Castle probably date back to the early 13th century, evidenced by the foundations of a residential tower from the middle of the same century. In the Middle Ages, the region around Bachem, to which the castle belonged, was divided between the Duchy of Jülich and Electoral Cologne. In 1583, the castle suffered destruction. After the Thirty Years' War, the tower and the south wing were rebuilt, supplemented by a three-arched bridge.
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: 50.8932, 6.8142