The Mont Royal fortress
The French Sun King, Louis XIV, left the fortress Mont Royal, in the period from 1687 to 1689, according to the plans of the fortress builder Sebastien Le Prestre, Seigneur de Vauban built. The main task of the fortress was to supply its fortress chain and control the central Rhineland. The French model fortress, however, was destroyed again by the French themselves from 1698 onwards, as they left the castle after the Peace of Rijswijck did not want to hand over to Holland or England.
With the help of the Reich Labor Service, the remains were dug up again from 1929 to 1937. This was under the direction of the home educator Dr. Ernst Wilhelm Spies, who carried out the excavations on Mont Royal using the original plans from the Paris archives. The discoveries can be viewed daily from Easter to October in the Middle Moselle Museum. Guided tours through the fortress ruins take place every first Saturday of the month in summer.
More about the fortress of Mont Royal at Wikipedia.