Suomenlinna

In the 18th century Sweden faced a growing Russian navy: Peter the Great had founded St Petersburg in 1703 and built the naval base of Kronstadt in its approaches. After the Russo-Swedish War of 1741 to 1743, the Swedish parliament decided in 1747 to fortify the frontier and to build a naval base at Helsingfors, now Helsinki, as a counter to Kronstadt. Augustin Ehrensvärd was put in charge, and work began in January 1748 on islands off the town.

The fortress was named Sveaborg, fortress of Sweden. Its plan adapted the principles of the bastioned star fort to a group of rocky islands, with a naval dockyard at its heart. More than 6,000 men worked on it in 1750 and 7,000 in 1755, when Helsingfors itself had about 2,000 residents. In the Finnish War of 1808 Russian forces besieged it, and in May its commander Carl Olof Cronstedt surrendered with almost 7,000 men; in 1809 Sweden ceded Finland, which became a grand duchy within the Russian Empire.

Russia added barracks, enlarged the dockyard and strengthened the defences. After Finland declared independence in 1917, the fortress was renamed Suomenlinna, fortress of Finland, on 12 May 1918. In 1918 and 1919 it held a prison camp where more than 1,000 of about 10,000 Red Guard prisoners died of hunger and disease. Most of the islands passed to civilian administration in 1973, the fortress was inscribed as a World Heritage site in 1991, and about 850 people live there today.