Hilgartsberg Castle lies on a mountain on the left bank of the Donau River. It was first mentioned in 1112. It was a fief of the Bishop of Bamberg and cared for by the Counts of Sulzbach. When the counts died out in 1188 the castle fell to a couple of sons of Frederick I, Holy Roman Emperor. They lent it out to Walchunus von Kamm.
In 1326 the castle came into the hands of the House of Eck. When Peter Ecker von Eck fell out of favor with Duke Albrecht I of Bavaria, the castle was besieged and conquered by the Duke in 1357. Albrecht then strengthened the castle and installed a castellan. Later it was lent out to several nobles. In 1617 it was used by the Fugger family, who considerably enlarged the castle after a big fire had damaged it in 1626.
In 1704, during the War of the Spanish Succession, Hilgartsberg Castle was occupied by Austrian troops. In 1742, during the War of the Austrian Succession, the Austrian troops returned and with help of Hungarian troops conquered and burned down the castle. After that it was a ruin and was never rebuilt.
Later the ruins were owned by a local brewer and the Bavarian State. And in the 1970s part of it served as the village school. At present Hilgartsberg Castle can freely be visited. It is used as a venue for cultural events.References:
First record of Kastelholma (or Kastelholm) castle is from the year 1388 in the contract of Queen Margaret I of Denmark, where a large portion of the inheritance of Bo Jonsson Grip was given to the queen. The heyday of the castle was in the 15th and 16th centuries when it was administrated by Danish and Swedish kings and stewards of the realms. Kastelhoma was expanded and enhanced several times.
In the end of 16th century castle was owned by the previous queen Catherine Jagellon (Stenbock), an enemy of the King of Sweden Eric XIV. King Eric conquered Kastelholma in 1599 and all defending officers were taken to Turku and executed. The castle was damaged under the siege and it took 30 years to renovate it.
In 1634 Åland was joined with the County of Åbo and Björneborg and Kastelholma lost its administrative status.