Berlanga de Duero Castle, which is now in ruins, dates back to the 15th century though it was built over a 10th-century Muslim fortress of which there are no remnants. It originally belonged to the Tovar family who ordered the construction of the village’s collegiate. This castle played an important role, along with the defensive wall, in defending the villages along the Douro riverbanks during the Muslim Conquest. Of the remains that are left of the castle, it is worth noting the keep which is in very good condition.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.