Villafuerte Castle was erected in the 15th century, forming pat of the defensive line drawn alongside of the river. Its first lord was García Franco, a Jew who later on converted to Christianity. It might have been built in order to control his properties.
Its layout is of the so-called 'tower castle'; an almost square, small enclosure with round towers (with a 3-meter diameter) at 3 corners and the keep at the 4th, much like other castles such as Torrelobatón Castle. The keep which has lost its crenellations, consists of 5 floors; 2 vaulted and 3 wooden ones. All the floors communicate by one narrow, spiral wall staircase. The entrance to the keep is through a doorway, on a height of 7 meters, which could be reached by another spiral staircase from the courtyard and a movable wooden footbridge. The tower has been restored and furnished. Today it houses a museum.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.