Bad Homburg Castle

Bad Homburg Castle (Schloss Bad Homburg) is a castle and palace that was first built in the 12th century. It was inherited by Hesse-Darmstadt after Prussia's annexation of Hesse-Homburg in 1866 following the Austro-Prussian War, becoming a summer residence for the kings of Prussia. William I stayed at the castle several times, as did his son and successor Frederick III and Frederick's wife Victoria. The castle was a particular favourite of Frederick and he and his successors added bathrooms, telephone rooms and electricity. --from Wikipedia