The Château de Robert le Diable (also known as Château de Moulineaux) was a feudal castle from the time of the Dukes of Normandy. It is named after Robert the Devil who was also known as Robert de Montgomery and Robert le Magnifique ('the magnificent'). He was the Duke of Normandy and father of William the Conqueror. However, there is no evidence that this person was involved in the construction.
The castle was built during the 11th and 12th centuries. It stands on a hill which dominates the River Seine, the view extending over the whole Rouen region, making it a particularly strategic location. It is known that the English King Richard I ('Lionheart') stayed here. His brother, King John ('Lackland') destroyed the castle during his struggle with the King of France Philip II Augustus. The castle was rebuilt in 1378 by the Lord of Sefton. During the Hundred Years War, the people of Rouen destroyed the towers to prevent the castle being used by the English. Half ruined, it is today furnished with various artefacts as well as reconstructed scenes of local history and life in the Middle Ages. The castle is privately owned.References:
The Petersberg Citadel is one of the largest extant early-modern citadels in Europe and covers the whole north-western part of the Erfurt city centre. It was built after 1665 on Petersberg hill and was in military use until 1963. It dates from a time when Erfurt was ruled by the Electors of Mainz and is a unique example of the European style of fortress construction. Beneath the citadel is an underground maze of passageways that can be visited on guided tours organised by Erfurt Tourist Office.
The citadel was originally built on the site of a medieval Benedictine Monastery and the earliest parts of the complex date from the 12th century. Erfurt has also been ruled by Sweden, Prussia, Napoleon, the German Empire, the Nazis, and post-World War II Soviet occupying forces, and it was part of the German Democratic Republic (East Germany). All of these regimes used Petersberg Citadel and had an influence on its development. The baroque fortress was in military use until 1963. Since German reunification in 1990, the citadel has undergone significant restoration and it is now open to the public as a historic site.