Kalmar Church was built of granite in the late 12th century. Around 1300 it was enlarged and modified to the aisleless Gothic church. In 1485 famous Albertus Pictor decorated walls and vaults with murals. Frescoes were restored in 1958 and still visible. Th current tower was added in 1830. There is font with a cuppa, made of red sandstone, from the late 1100s and medieval wooden sculptures (like a triptych from the mid-1400s) in the church.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.