Rupelmonde Castle was built by the Counts of Flanders in the 12th century directly opposite the mouth of the river Rupel into the Scheldt river to defend these rivers. It was a large fortress with 17 towers circled by a moat. From this castle toll was levied from passing ships. Later on the castle was also used as a state prison. This caused the castle to play a important role in the history of the region.
In 1678, when Spanish and Dutch troops were fighting against French troops, the castle was destroyed. The castle was never rebuilt and turned into a quarry for cheap building materials for the locals. In 1817 the castle ruins were demolished with exception of a base of a tower with some connecting wall fragments. On these remains then a tower out of red Tournai limestone was built by Baron De Feltz. This tower was used as a hunting pavilion.
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The Château du Haut-Koenigsbourg is situated in a strategic area on a rocky spur overlooking the Upper Rhine Plain, it was used by successive powers from the Middle Ages until the Thirty Years' War when it was abandoned. From 1900 to 1908 it was rebuilt at the behest of the German kaiser Wilhelm II. Today it is a major tourist site, attracting more than 500,000 visitors a year.
The first records of a castle built by the Hohenstaufens date back to 1147. The fortress changed its name to Koenigsburg (royal castle) around 1157. The castle was handed over to the Tiersteins by the Habsburgs following its destruction in 1462. They rebuilt and enlarged it, installing a defensive system designed to withstand artillery fire.
The fortification work accomplished over the 15th century did not suffice to keep the Swedish artillery at bay during the Thirty Years War, and the defences were overrun.