Ducové is famous for an archaeological site on the Kostolec hill, where an important Great Moravian castle has been unearthed. The castle, including a small palace, a Christian rotunda church, and a graveyard of local nobles, served as the administrative center of the Váh river valley during the 9th century and the first half of the 10th century. It was founded after the nearby Nitrian castle in Pobedim was destroyed during unification of Great Moravia by Mojmír I.
Ducové castle was destroyed itself by Magyar invaders around 955. Some parts of the castle (such as its palisades) have been reconstructed by archaeologists. Excavations of older settlements from the Stone Age, Bronze Age and the Roman era indicate that Ducové benefited from its location on the Amber Road well before the Great Moravian era.
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.