Santorini, is a part of an archipelago that took its current form after a series of serious volcanic eruptions. The islands that constitute the archipelago are those of Therasia, the uninhabited island Aspronisi and the residual volcanic islands Palaia Kammeni and Nea Kammeni.
Before a great eruption that occurred 3,500 years ago, they used to form one big round island called Strogili (which means circular). This historic eruption separated it and created the individual islands. Plus it gave Santorini its crescent shape, the extraordinary volcanic beaches and the jaw-dropping caldera.