Naples, Italy

Naples sits on the Bay of Naples with roughly 910,000 residents and traces its origin to Greek settlers who founded it as Neapolis, meaning "new city," in the 8th century BC. The 1,700-hectare historic centre is the largest UNESCO-listed old town in Europe, while the waterfront holds the 13th-century Castel dell'Ovo, the city's oldest castle, alongside the 1280 Castel Nuovo. The 1737 Teatro di San Carlo remains the world's oldest active opera house, and Raffaele Esposito invented the Pizza Margherita here in 1889. Mount Vesuvius, looming over the bay, last erupted in 1944 and is still classified as an active volcano.