Suomenlinna Tavel Guide
Built on six islands--Kustaanmiekka, Susisaari, Iso-Mustasaari, Pikku-Mustasaari, Länsi-Mustasaari and Långören, Suomenlinna is an inhabited sea fortress and a part of the Helsinki, the capital of Finland. As a UNESCO World Heritage site and a picturesque picnic site, it's popular with tourists and locals. So If you see only one place in Helsinki in the summer, make it Suomenlinna.
Today's Suomenlinna is still living in its own time with only old buildings, few cars, fewer than a thousand inhabitants and lots of old fortifications, catacombs and cast iron cannons. But it's not just a museum: the sprawling complex houses restaurants, cafes, theaters and museums, and is a very popular place for a picnic on a fine summer day, watching the vast passenger ferries drift by on their way to Estonia and St Petersburg.
The island itself is free, but you need to take a ferry to get there, which is charged. The HSL ferry from Market Square is the cheapest and most convenient way of getting there. The ferry is a part of the Helsinki local traffic, so if you have an HSL Day Ticket it includes ferry travel. The ferry runs approximately every half hour.