Near the German border, in Westerwolde (Southeast Groningen), is the fortress Bourtange.
In 1580 William of Orange gave the order to build a fort on the sand ridge in the Bourtanger moor, on the border of modern Germany. On the order of William Louis of Nassau the fortress was raised in 1593.
Between 1593 and 1851 Bourtange was an important fortress. An agrarian village came into being when the fortress was dismantled in 1851. Only a few buildings still remembered the glory of yesteryear. In the nineteen sixties the county of Vlagtwedde took the initiative to reconstruct the fortress. The plan was implemented between 1967 and 1992. Ramparts were again raised, ditches were dug and soldiers’ barracks were built.
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.