Fosteau Castle, locally known as Château du Fosteau, lies in the town of Leers-et-Fosteau, in the province of Hainaut in the Wallonia region in Belgium.
The oldest parts of Fosteau Castle date back to the late 14th century. At that time the castle was a rectangular moated fortified mansion and was owned by a Simon or Wauthier de Semonsies, a local lord. His eldest daughter, Jeanne, married Jean I de Sars probably just before 1400. Four generations of Knights of Sars succeeded each other here.
In the middle of the 16th century Fosteau Castle passed to a Louis de Zwenne, through marriage. In 1599, his son, Pierre, was forced to sell the castle due to financial difficulties. By that time the castle was in a dilapidated state. It was bought by Nicolas de Marotte who restored and enlarged the castle. One of the things he did was adding the extra floor out of brick on top of the earlier mansion.
During the 17th century the castle passed to an Andrien Jamblines through marriage. His great great grandson, Adolphe d'Aoust, inherited Fosteau Castle in 1794. Earlier during the 18th century a new wing had been added to the castle giving it an U-shaped ground plan.
In 1854, Fosteau Castle fell to the nephew of Adolphe, Jules-Edmond, Marquess of Aoust, whose daughter Hélène, married Henri Marie de Robin de Barbantane. During the 19th and 20th century the Barbantane family remodeled the castle several times and they added a second farmyard.
One of their descendants, Roseline de Robin de Barbantane, the wife of Baron Albert le Guay, lived in the castle until 1981. Then it was sold to its present owners, the Van Hoonacker family. They also restored the castle.
At present Fosteau Castle is private property but it can be visited for a small fee. A nice rural castle.