Famous cities of the world. Paris, France Paris

Athens, Greece

One of the world’s oldest cities is brimming with new life these days, but the appeal of Athens' beauty is its healthy mix of ancient and modern. Get your dose of history at the Acropolis, which provides both close-up views of the Parthenon and panoramic views of the city from its hilltop. Get similarly sweeping views without the heavy footwork at Lykavittos Hill, reachable via cable car. After all that antiquity, devote an afternoon to a site that's only a couple years old: The Renzo Piano-designed, $623 million Stavros Niarchos Foundation Cultural Center, which houses the National Opera and the National Library of Greece.

Beirut, Lebanon

Beirut's seaside glamour rivals that of any European riviera, with posh beach clubs and rooftop bars, palm tree-lined promenades, and hidden courtyards filled with bougainvillea. But here, glossy high-rises are juxtaposed against centuries-old mosques and souks, giving the city a timeless appeal you won't find anywhere else.

Lisbon, Portugal

You can't walk down a street in Lisbon without spotting something beautiful. Just check out the terra-cotta roofs of Alfama, or the neo-classical architecture on the riverfront Praça do Comércio. But really, the visual appeal of Lisbon can be summed up in just three words: tiles, tiles, tiles.

Florence, Italy

Italy has no shortage of beautiful cities, but Florence remains unrivaled in history, art, and architecture. You'll find traces of Renaissance aesthetics all over town, like the striking Santa Maria del Fiore (The Duomo) and Basilica of Santa Maria Novella. Meanwhile, Ponte Vecchio and the Uffizi remain essential photo backdrops.

Istanbul, Turkey

Istanbul continues to draw us in, whether it's through the frenetic opulence of the Grand Bazaar or the old-meets-new aesthetic of Karaköy. But the architecture still shines brightest here, with the Blue Mosque and Hagia Sophia featuring prominent displays of both Byzantine and Ottoman styles: Think massive domes, colored mosaics, minarets, and Islamic calligraphy.