Montclair castle was built by Arnulf von Walecourt in the late 12th century. The site was a fief from Trier archbishop. The castle was built to the site of old Frankish castle. In 1351 the castle was conquered and razed by the troops of Archbishop Baldwin of Luxembourg. Jakob von Sierck built the new castle in 1434-1439. It fell into disrepair and started to decay in the 17th century. Montclair was restored in 1992-1993.
References:The Gravensteen is a castle in Ghent originating from the Middle Ages. The name means 'castle of the counts' in Dutch. Arnulf I (918–965), Count of Flanders, was the first to fortify this place, building a medieval bastion on this high sand dune, naturally protected by the river Leie and its marshy banks. This bastion consisted of a central wooden building and several surrounding buildings, also in wood.
In the early 11th century, the wooden building was replaced by a stone residence, consisting of three large halls that made up three storeys, connected by a stone stairwell. The monumental stone staircase, the light openings, the fireplaces built into the walls and the latrines were signs of considerable luxury and comfort in those days. There was probably also a tower.