In 955, Almería gained the title of medina ('city') by the Caliph of Cordoba, Abd ar-Rahman III: construction of the defensive citadel, located in the upper sector of the city, began in this period. The alcazaba, provided not only with walls and towers but also with squares, houses and a mosque, was to be also the seat of the local government, commanding the city and the sea nearby.
The complex was enlarged under caliph Al-Mansur and, later, under Al-Jairan, first king of the independent taifa of Almería (1012–1028).
The first line of walls is a wide enclosure corresponding to the first Muslim military camp, used as shelter for the population in case of siege. For this task it was provided with large cisterns.
The first enclosure is separated by the second one by the so-called Muro de la Vela ('Wall of the Sail'), taking its name from a bell that warned the population in case of events such as the arrival of a ship in the port, danger, fires etc. This wall was built by King Charles III of Spain.
In the second enclosure was the residence for the governors, their soldiers and their servants. It included also the mosque, baths, tanks, tents etc.
The third enclosure, the most external, is also the most modern in the complex. After the Christian conquest of Almería, the Catholic monarchs Isabella I of Castile and Ferdinand II of Aragon had a castle built in the most elevated sector of the town, more apt to resist the new gunpowder artillery.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.