Imperial Palace, Gelnhausen
The Imperial Palace at Gelnhausen (called in German Kaiserpfalz Gelnhausen, Pfalz Gelnhausen or Barbarossaburg) is located on a former island in the Kinzig river in Gelnhausen, Hesse, Germany. == Site == The Palace was built during the decades of 1160–1180.
Source: Wikipedia — Imperial Palace, Gelnhausen (CC BY-SA 4.0)