Athens is the capital of Greece. It was also at the heart of Ancient Greece, a powerful civilization and empire. The city is still dominated by 5th-century BC landmarks, including the Acropolis, a hilltop citadel topped with ancient buildings like the colonnaded Parthenon temple. A volcano is a rupture in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface. On Earth, volcanoes are most often found where tectonic plates are diverging or converging, and most are found underwater. Santorini is one of the Cyclades islands in the Aegean Sea. It was devastated by a volcanic eruption in the 16th century BC, forever shaping its rugged landscape. The whitewashed, cubiform houses of its 2 principal towns, Fira and Oia, cling to cliffs above an underwater caldera (crater). Istanbul is a major city in Turkey that straddles Europe and Asia across the Bosphorus Strait. Its Old City reflects cultural influences of the many empires that once ruled here.The iconic Byzantine Hagia Sophia features a soaring 6th-century dome and rare Christian mosaics. Cappadocia, a semi-arid region in central Turkey, is known for its distinctive “fairy chimneys,” tall, cone-shaped rock formations clustered in Monks Valley, Göreme and elsewhere.