The magnificent Eriksberg Castle was built by statesman Erik Karlsson Gyllenstierna and completed after his death (1657) by his wife Beata von Yxkull. The castle was designed by famous architect Nicodemus Tessin the Elder. After possession of Gyllenstierna Eriksberg was left to decay, until it was restored in the 1800s by Carl Carlsson Bonde. Eriksberg is still privately owned by Bonde family, but the large park is open to the public. There are several form types, like Baroque and Italian park.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.