Burgruine Aggstein is the remnant of a castle on the right bank of the Danube, north of Melk. According to archaeological excavations of the foundations of the castle it has been inferred that the castle was built in the early part of the 12th century. The castle was built by Manegold III Aggsbach Getbeen of the Kuenringer family descent and his son Aggstein Manegold IV inherited it as a fiefdom of Bavaria. They started living in the castle from 1180 onwards. Its notoriety was due to the 'robber barons' of Schloss Schonbuhel and Burg Agstein' who imprisoned their rivals for ransom and tied them to a rock ledge all the time threatening to kill them by throwing them into the gorge. In 1181, it came into the possession of the Kuenringer Aggsbach-Gansbach. The castle was besieged during the revolt of the Austrian nobility against Duke Albrecht I in 1295/96. Kuenringer Leutold occupied the castle from 1348 to 1355 and then it fell into disrepair.
In 1429, Duke Albrecht V pledged to rebuild the ruined castle because of its strategical point on the Danube. The purpose was to collect taxes from passing boats. In 1438, he built a riverbank toll house to regulate shipping on the Danube and used it as a front to accumulate wealth by robbery from ships. Later, another dishonest baron, Georg von Stain, occupied the castle but in 1476 he was caught and expelled and was forced to surrender the castle. Duke Leopold III took over the castle in 1477. It was occupied with tenants and carers in order to stop the looting which had taken place on the river in previous decades.
In 1529, the castle was burned down by a group of Turks during the first Turkish siege of Vienna. It was rebuilt and provided with loopholes for defence with the help of artillery. In 1606, Anna Baroness acquired the castle, but after her death, the castle was neglected. In 1685, the castle became the property of Count Ernst Rüdiger von Starhemberg. Then in 1819, one of his descendants, Ludwig Josef Gregor von Starhemberg, sold the castle to Count Franz von Beroldingen who renovated the castle in the 19th century. The Beroldingen family owned the castle until 1930 when the estate and the ruins of Schönbühel Aggstein were sold to Count Oswald von Seilern Aspang.References:
Varberg Fortress was built in 1287-1300 by count Jacob Nielsen as protection against his Danish king, who had declared him an outlaw after the murder of King Eric V of Denmark. Jacob had close connections with king Eric II of Norway and as a result got substantial Norwegian assistance with the construction. The fortress, as well as half the county, became Norwegian in 1305.
King Eric's grand daughter, Ingeborg Håkansdotter, inherited the area from her father, King Haakon V of Norway. She and her husband, Eric, Duke of Södermanland, established a semi-independent state out of their Norwegian, Swedish and Danish counties until the death of Erik. They spent considerable time at the fortress. Their son, King Magnus IV of Sweden (Magnus VII of Norway), spent much time at the fortress as well.
The fortress was augmented during the late 16th and early 17th century on order by King Christian IV of Denmark. However, after the Treaty of Brömsebro in 1645 the fortress became Swedish. It was used as a military installation until 1830 and as a prison from the end of the 17th Century until 1931.
It is currently used as a museum and bed and breakfast as well as private accommodation. The moat of the fortress is said to be inhabited by a small lake monster. In August 2006, a couple of witnesses claimed to have seen the monster emerge from the dark water and devour a duck. The creature is described as brown, hairless and with a 40 cm long tail.