Sprawling along the edge of the Thermaic Gulf, Thessaloniki is a seaside showcase of Greek history from ancient Roman and Byzantine ruins to the modern high-rises lining its beaches. Plus, after sundown, Greece’s cultural capital hums with some of the best nightlife options in the Aegean.

Barcelona feels a bit surreal – appropriate, since Salvador Dali spent time here and Spanish Catalan architect Antoni Gaudí designed several of the city’s buildings. Stepping into Gaudí’s Church of the Sacred Family is a bit like falling through the looking glass - a journey that you can continue with a visit to Park Güell. Sip sangria at a sidewalk café in Las Ramblas while watching flamboyant street performers, then create your own moveable feast by floating from tapas bar to tapas bar.

Golden palaces, floating markets, majestic porcelain-laid spires…you've never seen a capital city quite like Bangkok. Visit Pratunam or Siam Square for premium shopping, then unwind in the European-style gardens of Dusit. Thon Buri is home to the awesome Wat Arun temple, and over in Phra Nakhon, you’ll find the Wat Pho temple of the Reclining Buddha. Savor mango sticky rice at a food stall before taking in the gilded splendor of the Grand Palace.

The Singapore cityscape looks like it was ripped from the pages of a science fiction comic book. If you’re hungry for a true Singapore experience, sample the myriad street foods or take a cultural cooking class. The Botanic Gardens and the Gardens By the Bay offer a slice of horticultural heaven, and the observation deck of the Sands SkyPark makes you feel like you’re high above the clouds. The banks and walkways along the Singapore River bustle with local activity.

The charming Vietnamese capital has aged well, preserving the Old Quarter, monuments and colonial architecture, while making room for modern developments alongside. Hanoi may have shrugged off several former names, including Thang Long, or "ascending dragon," but it hasn't forgotten its past, as sites such as Ho Chi Minh's Mausoleum and Hoa Lo Prison attest. Lakes, parks, shady boulevards and more than 600 temples and pagodas add to the appeal of this city, which is easily explored by taxi.