A castrum is mentioned on the site of Château de Flamarens in 1289, and is believed to have been remodelled in the 14th century. Additional building work and alterations were made some time between 1469 and about 1475 by Jean de Cazanove for Jean de Grosolles. The northern part was built before 1536 by Georges Dauzières for Arnaud de Grossolles. Alterations were made to the windows and interior decoration in the 18th century. The castle was partially destroyed by fire in 1943.
The castle is privately owned.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.