Ahrensbök Charterhouse was a former Carthusian monastery or charterhouse established in 1397. The estates with which it was endowed reached as far as Scharbeutz on the Bay of Lübeck.
During the Reformation the monastery was secularised, and with its estates fell into the hands of John II, Duke of Schleswig-Holstein-Sonderburg, in 1584, who had the buildings demolished.
The building materials were used between 1593 and 1601 for the construction of the castle in Ahrensbök, Schloss Hoppenbrook, which was the principal residence between 1623 and 1636 of the ruler of the newly formed Duchy of Schleswig-Holstein-Sonderburg-Plön while Duke Joachim Ernst I's new castle in Plön was under construction. Once Schloss Plön was finished, the ducal residence was moved there from Ahrensbök, leaving Schloss Hoppenbrook as a secondary residence.
After the death there in 1740 of Duchess Juliane Luise, widow of Joachim Frederick, Duke of Schleswig-Holstein-Sonderburg-Plön, Schloss Hoppenbrook was demolished. The Rathaus of Ahrensbök now stands on its site, in a park in which ditches from the previous castle complex can still be made out.
The only surviving building from the time of the Carthusians is the Brick Gothic St. Mary's church - Marienkirche - which in fact was begun in the first quarter of the 14th century and thus predates the monastery itself: when the charterhouse was established it was taken over for use as the monastery church. It was extended several times, and in 1400 the polygonal quire was added. The tower, with an inscribed sandstone tablet over the portal, was not added until 1761.References:
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.