Kyminlinna - Credit: Wikimedia Commons
Kyminlinna (literally, 'the castle of Kymi') is a fortress located in the northern part of island of Hovinsaari in Kotka, on the south coast of Finland. Kyminlinna is part of the South-Eastern Finland fortification system built by Russia after the Russo-Swedish War of 1788-1790. Kyminlinna formed the northern part of a double fortification, together with Ruotsinsalmi sea fortress, where Kyminlinna was intended to repulse land-based attacks along the King's Road. Read more on Wikipedia
Source: en.wikipedia.org