Geography thumb|upright= 1.2|City map of Suomenlinna The Suomenlinna district of Helsinki lies southeast of downtown Helsinki and consists of eight islands. Five of the islands are connected by either bridges or a sandbar landbridge. Länsi-Mustasaari (sv: Västersvartö) is bridged to Pikku Mustasaari (sv: Lilla Östersvartö), which is bridged to Iso Mustasaari (sv: Stora Östersvartö), which is bridged to Susisaari (sv: Vargö), which was connected to Susiluoto (sv: Vargskär) by filling in the separating waterway during the Russian period. This island, which has the greatest concentration of fortifications was renamed Gustavssvärd (King Gustav's sword) (fi: Kustaanmiekka) during the construction by Sweden. The three unconnected islands are Särkkä (sv: Långören), Lonna (sv: Lonnan), and Pormestarinluodot (sv: Borgmästargrundet). The total land area is . Instead of using the normal Finnish postal addressing scheme (consisting of a street name and a house number), the addresses at Suomenlinna consist of a letter code for the island and then a house number. For example, C 83 is house #83 on Iso-Mustasaari (code C). The postal code for the Suomenlinna district is 00190.
Geography thumb|upright= 1.2|City map of Suomenlinna The Suomenlinna district of Helsinki lies southeast of downtown Helsinki and consists of eight islands. Five of the islands are connected by either bridges or a sandbar landbridge. Länsi-Mustasaari (sv: Västersvartö) is bridged to Pikku Mustasaari (sv: Lilla Östersvartö), which is bridged to Iso Mustasaari (sv: Stora Östersvartö), which is bridged to Susisaari (sv: Vargö), which was connected to Susiluoto (sv: Vargskär) by filling in the separating waterway during the Russian period. This island, which has the greatest concentration of fortifications was renamed Gustavssvärd (King Gustav's sword) (fi: Kustaanmiekka) during the construction by Sweden The three unconnected islands are Särkkä (sv: Långören), Lonna (sv: Lonnan), and Pormestarinluodot (sv: Borgmästargrundet). The total land area is . Instead of using the normal Finnish postal addressing scheme (consisting of a street name and a house number) the addresses at Suomenlinna consist of a letter code for the island and then a house number. For example, C 83 is house #83 on Iso-Mustasaari (code C). The postal code for the Suomenlinna district is 00190.