Lochranza Castle dates from the 13th century when it was owned by the MacSweens. In 1262, King Alexander III granted the castle and its lands to Walter Stewart, the Earl of Menteith. It is believed that Robert the Bruce landed at Lochranza in 1306 on his return from Ireland to claim the Scottish throne. By 1371, the castle was the property of Robert II. It is thought that at this time it was used as a royal hunting lodge.
During the 1490s, James IV used the castle in his campaign against the Lord of the Isles and the Clan MacDonald. In 1614 it was occupied by James VI and in the 1650s it was used by Cromwell. By 1705, Lochranza Castle was the property of the Hamilton family, after it was purchased by the Duchess of Hamilton. The Hamiltons had owned other estates on the Isle of Arran so eventually sold it to the Blackwood-Davidson family who used it as their principal seat. During the 18th century, the castle fell into disuse and was abandoned. The castle is now in the care of Historic Scotland.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.