Helsinki

Helsinki needs 3 days: Helsinki Cathedral, with its white neoclassical facade over Senate Square, on one, the Suomenlinna sea fortress, on an island 15 minutes away by ferry, on another, and the Kauppatori market by the harbor on the third. June-August brings very long days, with sun almost until midnight. It's expensive, among Europe's priciest capitals. It's one of the world's most influential design capitals -birthplace of minimalist Scandinavian design and brands like Marimekko and Iittala- and its Suomenlinna fortress, built in the 18th century across six islands, is a UNESCO World Heritage Site.