Berlin is an edgy city, from its fashion to its architecture to its charged political history. The Berlin Wall is a sobering reminder of the hyper-charged postwar atmosphere, and yet the graffiti art that now covers its remnants has become symbolic of social progress. Check out the Weltzeituhr (world time) Clock, topped by a model of the solar system, then turn back time by dining at the historic Zur Letzten Instanz, a 16th century restaurant that was frequented by Napoleon and Beethoven.

Copenhagen was once a Viking fishing settlement, and you can still find traces of the Norse explorers here. Visit reconstructed villages, the remains of a 1,000-year-old castle, and museums dedicated to the notorious raiders. Copenhagen also features a blend of modern architecture and historical artifacts such as the Round Tower observatory – a wonderful example of 17th-century architecture. Art galleries, narrow streets, canals, parks, and Baroque churches round out the city’s cultural attractions.

This city, full of colorful homes, canals and bridges, is one of Europe's most picturesque capitals. Must-sees on any visitor's itinerary include the Anne Frank House, the Van Gogh Museum and the world's only floating flower market. Rent a bike and join thousands of locals navigating Amsterdam's labyrinthine streets, or just take in the sights on foot. For an unusual and memorable alternative to hotels, consider staying in a houseboat.

From Shoreditch’s swaggering style to Camden’s punky vibe and chic Portobello Road, London is many worlds in one. The city’s energy means that no two days are the same. Explore royal or historic sites, tick off landmarks from your bucket list, eat and drink in exclusive Michelin-starred restaurants, enjoy a pint in a traditional pub, or get lost down winding cobbled streets and see what you stumble across – when it comes to London, the possibilities are endless.

Sitting on the edge of the Baltic, the modern, cosmopolitan city of Helsinki is the World Design Capital for 2012. The beauty of the surrounding nature blends seamlessly with high-tech achievements and contemporary trends. Walking tours of the city center show layers of history, while modern architecture and cutting-edge style stake the city's claim to the future. Choose Helsinki during its endless summer days or get adventurous on crisp, snowy winter nights.

Walk the Freedom Trail the first time you visit Boston and you'll quickly get a sense of this coastal city's revolutionary spirit and history. But make sure you also explore some of Boston's fine museums (try the Isabella Stewart Gardner, featuring masterpieces displayed in their collector's mansion) and old neighborhoods (like the North End, Boston's Little Italy). You can't claim to have experienced real Boston culture, though, until you've watched a Red Sox game from the bleachers.

Conquering New York in one visit is impossible. Instead, hit the must-sees – the Empire State Building, the Statue of Liberty, Central Park, the Metropolitan Museum of Art – and then explore off the beaten path with visits to The Cloisters or one of the city’s libraries. Indulge in the bohemian shops of the West Village or the fine dining of the Upper West Side. The bustling marketplace inside of Grand Central Station gives you a literal taste of the best the city has to offer.

From the National Mall’s monuments and memorials to vibrant neighborhoods filled with character and charm, DC is a world-class destination featuring breathtaking views, award-winning hotels and hundreds of free things to do. Experience outstanding performing arts at acclaimed theaters, shop in historic Georgetown, hear great live music at legendary venues, enjoy sporting entertainment from six professional franchises and be dazzled by a flourishing dining scene with Michelin-starred restaurants.