The Château d'Olhain is probably the most famous castle in the Artois region. It was a major stronghold for the Artois in medieval times and testimony to the power of the Olhain family.
There has been a castle on this site since the early 13th century. The present construction is largely the work of Jean de Nielles, who married Marie d’Olhain at the end of the 15th century.
Adapted from Wikipedia
en.wikipedia.org/wiki/Ch%C3%A2teau_d'Olhain 