The Church of St. Lawrence was built in the 13th century, probably only after the foundation of the town in 1250. Construction works could last until the end of the third quarter of the 13th century. As early as 1285, there was a first record of the local priest Rudolf, who then appeared as a witness on the document.
In 1428, the Hussites plundered and burned down the church of which bare walls remained. The reconstruction continued with problems until 1472, when the church was re-consecrated. During it, a new, larger chancel was built.
In 1560, the church was damaged again by a fire, after which its facades were covered with Renaissance decorations (corner bossage) during renovation. The church survived in this condition until 1729-1733, when it was rebuilt in the baroque style at the request of the bishop of Wrocław, Francis Ludwik von Neuenburg. The old nave and the gothic chancel were almost completely rebuilt, the older walls were dismantled and only partially used in new building. In 1841, two early modern helmets were erected by the carpenter Francis Berger on the western towers, and at the same time the front wall between the towers was raised to the height of the crowning cornice. The helmets of the towers were replaced once again at the beginning of the 20th century.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.