On a sunny weekday afternoon in June, Helsinki’s Suomenlinna sea fortress was hopping. Ferries loaded with visitors came and went. Locals wandered the miles of trails at this sprawling UNESCO World Heritage Site. Tourists learned about Scandinavian military history and visited museums. There was even a wedding going on, complete with women tottering around the old fort in high heels.

Photo by Teresa Bergen

Finland was part of Sweden when the Swedes started to build the sea fortress, then called Sveaborg, in 1748. Since Sweden was warring with Russia, the country wanted to protect its eastern border against Russian attacks. It was Sweden’s biggest construction project at the time. 

The fort held out for over half a century before surrendering to Russian forces in 1808. Suomenlinna bears the marks of history. It was heavily damaged during the Crimean War in 1855. During the First World War (1914–1918), the fort was part of the Naval Fortress of Peter the Great, protecting the Russian capital St. Petersburg. The area housed a prison camp during the Finnish Civil War in 1918. More than a thousand prisoners died from disease, hunger, or execution.

Photo by Teresa Bergen

The grim, multi-layered history contrasts with the fun of a visit today. The fortress is a 15-minute ferry ride from downtown Helsinki. Restaurants, cafés, museums, and art and craft studios are open year-round. In summer, locals attend a popular outdoor theater. About 800 people live on the island.

Suomenlinna’s streets have no names, so it can be challenging to find your way about. Many tourists stick to what is known as the Blue Route, a mile-long trail that hits some of the fortress’ most important points. You start at the ferry landing and follow the blue signs. While Suomenlinna totals eight small islands, only five are connected by bridges or sandbars.

Beware the hissing geese and swooping seagulls. / Photo by Teresa Bergen

During my visit, I strayed from the Blue Route and wandered wherever whim took me. Every turn on paths and cobblestoned streets brought me to a new sea view or a bunker dug into a hillside.

One of the island’s explorable buildings. / Photo by Teresa Bergen

The site’s six museums feature everything from toys to military history. In some places, you can venture into old buildings. If you’re visiting Helsinki, an afternoon exploring Suomenlinna is a great way to learn some history, enjoy a long walk, and breathe in the fresh sea air.