Basilica of Our Lady of the Assumption (Basilica di Nostra Signora Assunta) was constructed during 1610–1624. The Baroque-style facade was added in 1932, design of the architect Piero de Barbieri; the sculptor Luigi Venzano contributed the facade statues of St. John the Baptist and St. Joseph, while the central relief depicts the Madonna. The interior was decorated across the centuries and includes works by Giulio Benso, Domenico Piola, Nicolò Barabino, and Gian Stefano Rossi.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.