Suomenlinna Sea Fortress is a UNESCO World Heritage Site located on a cluster of islands just off Helsinki’s coast, renowned for its impressive 18th-century military architecture and rich, layered history. Built by Sweden starting in 1748 to defend against Russian expansion, the fortress—originally called Sveaborg—was later expanded by Russian forces after their takeover in 1808, and finally served Finland after independence in 1917. Today, Suomenlinna covers six islands with over 200 buildings and six kilometers of defensive walls, blending bastions, tunnels, dry docks, and historic barracks into the rugged landscape. Visitors can explore highlights such as the iconic King’s Gate, the Great Courtyard, old bunkers, and the last surviving Finnish submarine. The site features six museums, numerous cafés and restaurants, and scenic coastal trails perfect for picnics or sunbathing. Suomenlinna is accessible year-round by ferry from Helsinki’s Market Square, making it easy to experience its unique combination of history, architecture, and natural beauty.
Helsinki FinlandSuomenlinna Sea Fortress is located on a group of eight islands, with six of them fortified, about 4 km southeast of Helsinki's city center. The fortress is a UNESCO World Heritage Site, showcasing stunning bastion fortifications and a rich history dating back to the 18th century. You can explore the Suomenlinna Museum, Ehrensvärd Museum, and the submarine Vesikko, which are part of the fortress. The area also features various restaurants, cafes, and artisan workshops. To get there, take the water bus (number 94) from Market Square (Kauppatori) in Helsinki. Once on the island, you can enjoy guided walking tours, visit the craft shops, or simply take in the picturesque views ¹ ².