Origins of the Château Bilquin de Cartier can be traced back to the around 1635, when the Honoré family built a castle on the Sambre river bank. The place had formerly been occupied by a seigneurial manor which was destroyed on 21 July 1554.
In 1667, the unfinished Spanish fortress of Charleroy was captured by Louis XIV's troops during the War of Devolution. As the castle in Marchienne was located in neutral territory (under authority of the Prince-Bishopric of Liège), it was used as a hospital for both French and Spanish soldiers.
In 1695, the castle was bought by Guillaume de Bilquin, a wealthy forge owner, who completes and enhances it. Later the castle became the property of the Cartier de Marchienne family. It was severely damaged by a fire in 1932, and bought over by the municipality of Marchienne-au-Pont in 1938, ending more than two centuries of ownership by the Cartier family.
The castle today hosts a public library on the ground floor (Bibliothèque Marguerite Yourcenar), and administrative services of the Walloon region on the first floor.
The Château de Foix dominates the town of Foix. An important tourist site, it is known as a centre of the Cathars. Built on an older 7th-century fortification, the castle is known from 987. In 1002, it was mentioned in the will of Roger I, Count of Carcassonne, who bequeathed the fortress to his youngest child, Bernard. In effect, the family ruling over the region were installed here which allowed them to control access to the upper Ariège valley and to keep surveillance from this strategic point over the lower land, protected behind impregnable walls.
In 1034, the castle became capital of the County of Foix and played a decisive role in medieval military history. During the two following centuries, the castle was home to Counts with shining personalities who became the soul of the Occitan resistance during the crusade against the Albigensians.