Stockholm's approach through the archipelago is breathtaking. Spread over 14 islands and crossed by 57 bridges, it's called "the city that floats on water." Visit Djurgården for the Vasa Museum and the Skansen open-air museum, wander Gamla Stan's medieval streets, and see nearby UNESCO sites: Birka, Skogskyrkogården, and Drottningholm Palace, home to the royal family since 1662.

Tallinn's UNESCO-listed Old Town is one of Europe's best-preserved medieval cities, with 13th-16th century churches, homes, and public buildings from Hanseatic merchants. Highlights include St. Olaf's Church, Alexander Nevsky Cathedral, Toompea Castle, and the Gothic town hall. Finish with a stroll in Kadriorg Park and its art museum in an 18th-century Russian palace.

Helsinki, Finland's capital and largest city, is a cultural hub with museums, galleries and theaters, including the Ateneum's nearly 30,000 works of art. Rebuilt under Russian rule in the 19th century, its neoclassical center features Senate Square, boulevards, parks and grand architecture. Market Square offers local crafts and salmon soup. Nearby Suomenlinna, a UNESCO fortress island reached by ferry, has museums and parkland.

Riga, Latvia's capital, is a multicultural delight. Its UNESCO-listed Old Town has Europe's finest Art Nouveau architecture, while Riga Cathedral dominates the skyline and houses one of the world's largest pipe organs. Riga Central Market, set in former airship hangars, is Europe's largest indoor market. Nearby are Vermanes Garden and, outside the city, the lakeside Latvian Ethnographic Open-Air Museum.

Gotland is a quiet, unhurried contrast to modern Sweden, rich in prehistoric mysteries, Viking treasures and medieval heritage. Visby, the only town, is ringed by 13th-century walls, towers and moats and showcases Hanseatic-era warehouses, guild houses and merchant homes. Beyond it lie beaches, cliffs, fishing villages, hamlets and burial sites, with the Gotland Museum displaying Bronze Age artefacts, Viking silver and picture stones.

Karlskrona blends naval heritage, a friendly feel, and easy access to outdoor adventures. In 1680, Karl XI chose the southern archipelago as Sweden's naval base. Trossö's 17th-century grid is still the Baroque heart of the city, now spread over 33 islands. From the town square and its landmarks to the Naval Port, Naval Museum, and Björkholmen, many sights are walkable. The old fish market is now the gateway to the archipelago.

Perched on a harbor rock, the Little Mermaid welcomes visitors to Copenhagen, a lively Danish capital famed for happiness, good food, free education and healthcare, and a 37-hour work week. The city blends modern architecture, world-class museums, charming canals, and Old Town streets in the world's oldest kingdom, plus 15 Michelin-starred restaurants and Strøget, the world's longest pedestrian shopping street.