Schachenstein Castle was the last hill castle to be built in the Styria. It was built in 1464 by Abbot John II Schachner of Lambrecht as a summer residence and lordly manor. It was extended in 1630 and 1740. From the end of the 18th century the castle lost its significance and fell into ruins.
The main purpose of the fortification was as a home and summer residence of the abbots of St. Lambrecht's Abbey as evinced by a large number of historic records. Subsequently, it was used to seal off the Mariazell road and protect the population of the Aflenz valley - who were looked after by the abbey - as well as providing a refuge during Turkish and Hungarian invasions.
The site of castle was an outstanding choice: some 640 above sea level on rocks forming the southern spur of the Schöckelberg. It is situated on an easily defended constriction of the road from Einodgräben to Mariazell, which was originally also guarded by a fortified gateway.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.