Kastelholm Castle is a historic fortress located on the island of Åland, Finland. Built in the late 14th century, it served as a royal residence and military stronghold. The castle features a mix of medieval architecture and scenic views of the surrounding landscape, making it a popular tourist destination. Today, Kastelholm Castle is partially restored and houses a museum that showcases its history and significance. Visitors can explore the ruins, learn about the Åland Islands heritage, and enjoy various cultural events held on the castle grounds throughout the year.