Of all the awe-inspiring antiquities in Greece, Delos is in a league of its own—a whole island of splendid ruins just an occasionally choppy half-hour boat ride from the hurly-burly of Mykonos. The most sacred sanctuary in ancient Greece, this was the birthplace of Apollo, god of light, and his twin sister, Artemis, goddess of the moon. (Under the August full moon, musicians perform among the ruins—an unforgettable experience.) Signage is minimal, so hire a guide to provide running commentary as you explore temples, cisterns, a theater, and a sacred lake. Visitors can stay no more than four hours, and swimming is forbidden. There’s a small canteen, but bring plenty of water, a hat, and sunscreen.