Biljoen estate was first mentioned in 1076. In 1530 Charles, Duke of Guelders, built the first castle and it was rebuilt by Alexander van Spaen (1619–1692) into the present day castle with four equal corner towers. The family Van Spaen rebuilt the castle again in the the 18th century. In 1795 French troops were quartered in the castle. After they left the castle was plundered and the interior largely destroyed. The damage was restored with amongst others ornamental plaster and ceiling paintings.
The estate was originally called Broekerhof, and was a place where taxes were collected. In 1076 it was donated by Henry IV, Holy Roman Emperor to the Sint-Pieter Chapter in Utrecht. In 1530 it was sold to Charles, Duke of Guelders. He in turn had to sell it again in 1535 because of debts. It came into possession of Charles' general Roelof van Lennep. Roelof's son Carl, mayor of Arnhem, inherited it in 1546. His son Roelof inherited it in turn in 1567. After family divisions it was sold to the baronial family Van Spaen in 1661. In 1849 baron Van Hardenbroek allowed Anna Pavlovna of Russia to use it temporarily. In 1872 it was inherited by the family Lüps, until 2008.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.