Part of the Cyclades island group, Santorini (officially known as Thira, a name that encompasses the volcanic islets within Santorini’s orbit) sits in the Aegean Sea, roughly halfway between Athens and Crete. The island is shaped like a wonky croissant, and the neighboring islets hint at the fact that Santorini was once circular. It was known as Strongili (the Round One). Thousands of years ago, a huge volcanic eruption caused the center of Strongili to sink, leaving a caldera (or crater) with towering cliffs along the east side, now Santorini’s trademark landscape.Santorini’s commercial development is focused on the caldera-edge clifftops in the island’s west, with large clusters of whitewashed buildings nesting at dizzying heights, spilling down cliffsides and offering gasp-inducing views from land or sea. Fira, the island’s busy capital, sprawls north into villages called Firostefani (about a 15-minute walk from Fira) and Imerovigli (the highest point of the caldera edge, about a 30-minute walk from Fira). A path running through these villages is lined with upmarket hotels, restaurant terraces and endless photo opportunities.