Travel by public ferry to tour Finland’s signature 18th-century sea fortress, straddling several small islands in Helsinki harbor. Suomenlinna is both a major military monument and a UNESCO World Heritage site, built to safeguard against the threat of Russian invasion back in the days when Sweden ruled Finland. Its military shipyard was one of the world’s largest dry-docks and Suomenlinna was considered on par with the great maritime fortifications at Gibraltar. Today, 250 years on, the citadel remains carefully preserved and makes a fascinating place to explore and learn about. During your walking tour around the Suomenlinna grounds, you’ll soon realize that this place is more than a fortress: the complex is really a city within the city of Helsinki, boasting its own library, health center, fire brigade and school. There’s even a WWII-vintage submarine parked along the coastline, a restored vestige of Finland’s flareup-prone territorial tug-of-war with Russia. After your formal Suomenlinna tour, the ferry crossing back to the Market square, where you will some short free time to explore on your own, before going back to the ship