Wikipedia
Kyminlinna, ″the castle of Kymi″, is a fortress located in the northern part of Hovinsaari island in Kotka, Finland. Kyminlinna is part of the South-Eastern Finland fortification system built by Russia after Russo-Swedish War of 1788-1790. Kyminlinna formed the northern part of a double fortress together with Ruotsinsalmi sea fortress, where Kyminlinna was intended to repulse land-based attacks along the King's Road.
Kyminlinna is a five-corner caponier fortress approximately 800 metres in diameter. The surface area of the fortress is approximately 74 hectares and it forms the greater part of the Kyminlinna neighbourhood in Kotka. The fortress is surrounded by incomplete moats, which also form a part of the ditch system intended to keep the ground dry. The eastern part of Kyminlinna ramparts are cut by the Kotka railway built in 1890 and the Kymintie road built in early 20th century. National road 7 cuts the outer ramparts of the southern part of the fortress. The fortress area has 23 buildings, most of which have been empty after Finnish Defence Forces ceased using the fortress.