The Pertteli Church was built probably between years 1500 and 1520 and was dedicated to St. Bartholomeus. First record of the local Uskela parish is from the 14th century and there has been at least one wooden church in Pertteli before. The original stone church was enlarged in the 18th and 19th centuries.
Finnish National Board of Antiquities has named the ancient road ("Hiidentie") and the church area as national built heritage.
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.