The castle of Ventimiglia is an ancient four towers castle which was built at the end of the 14th century by the Ventimiglia family on the top of Mount Bonifato near Alcamo.
Enrico Ventimiglia, the son of Guarnieri Ventimiglia whom he succeeded to, declared that he had this castle built on Mount Bonifato as a protection from possible attacks. According to different interpretations, the castle, instead, would date back to an anterior period.
The castle was destroyed in 1243 by order of Frederick II; it was rebuilt by the Ventimglia family before 1391 at her own expense.
Originally the castle had four towers and a rectangular trapezoid plan. The only remaining tower is the donjon or 'Torre maestram', that initially had three floors: you could enter it through a wooden ladder at the first floor. This tower is located on the north-west and had a rectangular plan with walls 2.2 m thick. It was the most important in the castle because, thanks to its impressiveness and position, this was a point of strategic sighting as they could check the road leading to the castle, as far as the entrance door, situated on the south-west side.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.