The Château des Tours was built in the 14th century. At that time it had three towers: one had a polygonal interior and was the dungeon, and the others were circular flanking an oblong building on the east and west corners of its south face; then, at the same corners on the north face, there are sentry boxes with Corbels. The oldest part is in the south of the present castle and is also a little higher.
North of the original castle there was a courtyard formed by the castle and crenellated walls outside with wide and deep ditches below. These ditches remain but the walls were replaced in the 16th century by rectangular buildings. At the east and west corners of the north facade there are two round towers, less high than the others, but topped like them with machicolations. There is a door between these two towers above which are the Arms of Calvimont carved on a large stone: they have lain since 1793 a few steps in front of the door.
The castle was restored by Viollet-le-Duc in the 19th century.References:
The Château d'Olhain is probably the most famous castle of the Artois region. It is located in the middle of a lake which reflects its picturesque towers and curtain walls. It was also a major stronghold for the Artois in medieval times and testimony to the power of the Olhain family, first mentioned from the 12th century.
The existence of the castle was known early in the 13th century, but the present construction is largely the work of Jean de Nielles, who married Marie d’Olhain at the end of the 15th century.
The marriage of Alix Nielles to Jean de Berghes, Grand Veneur de France (master of hounds) to the King, meant the castle passed to this family, who kept it for more than 450 years. Once confiscated by Charles Quint, it suffered during the wars that ravaged the Artois. Besieged in 1641 by the French, it was partly demolished by the Spaniards in 1654, and finally blown-up and taken by the Dutch in 1710. Restored in 1830, it was abandoned after 1870, and sold by the last Prince of Berghes in 1900. There is also evidence that one of the castles occupants was related to Charles de Batz-Castelmore d'Artagnan, the person Alexandre Dumas based his Three Musketeers charictor d'Artagnan on.
During the World War I and World War II, the castle was requisitioned first by French troops, then Canadian and British soldiers. The current owner has restored the castle to its former glory.