The crown of the region's historical heritage is the Chateau d'Olhain, the best preserved of Medieval castles in the North of France. Entirely made of sandstone, it took two centuries to build, from the 13th to the 15th century. The original layout remains intact, with its bailey enclosed inside the walls and its moat still mostly filled with water. Originally, it belonged to the Olhain family, one of the oldest noble families of teh Artois, but it was abandoned in 1870 by the last lord, who did not leave an heir. In 1900, the castle was sold to the ancestor of the current owner, who was interested mainly in the agricultural lands. The castle was included in the sales contract, as a "burden". You can walk along the moat, visit the chapel and the vaulted cellars, explore the attics, go down to see the rooms on the dungeon floor, and climb the watchtower.