CASTLES SUND

Kastelholm Castle rises on the Åland Islands in Finland, approximately 25 kilometres northeast of Mariehamn, overlooking a fjord near the village of Kastelholm. First constructed in the 1380s during the island's period as part of the Swedish Empire, it served as a vital military and administrative centre for the region. In the 15th and 16th centuries, the fortress became an important stronghold held by Swedish and Danish nobles and kings, with King Gustav I briefly residing there before claiming the Swedish throne. Successive rulers maintained and expanded the castle across two centuries, though damage during the 1599 civil war and a devastating fire in 1745 reduced it to ruins. Partial restoration occurred in the 20th century, and since the 1990s, Kastelholm has functioned as a museum and key cultural site. As one of only five surviving medieval castles in Finland with significant architectural merit, alongside Hämeenlinna, Olavinlinna, Raseborg, and Turku, it represents an important link to Scandinavian medieval history and strategic Baltic defence.

Bomarsund Fortress stands as dramatic ruins on the Åland Islands in Finland, representing a failed chapter in 19th-century military architecture. Constructed between 1832 and 1854 when Åland was Russian territory, this ambitious stronghold was designed to house thousands of troops—originally planned for 4,000–5,000 soldiers—and serve as a formidable defensive structure. However, the fortress met its decisive end during the 1854 Battle of Bomarsund in the Crimean War, when British and French forces captured it from the Russians after a week-long siege. The assault revealed the fortress's incompleteness: of 12 planned towers, only two had been finished by the time war erupted. Following this defeat, Åland was declared a demilitarised zone in 1856—a status that persists today. The ruins of Bomarsund have become one of Åland's most remarkable historical monuments and a popular visitor attraction, offering tangible evidence of 19th-century international conflict and geopolitical strategy in the Baltic region.