Santorini (, ), officially Thira (Greek: Θήρα ) and classical Greek Thera (English pronunciation ), is an island in the southern Aegean Sea, about 200 km (120 mi) southeast from the Greek mainland. It is the largest island of a small circular archipelago, which bears the same name and is the remnant of a caldera. It forms the southernmost member of the Cyclades group of islands, with an area of approximately 73 km2 (28 sq mi) and a 2011 census population of 15,550. The municipality of Santorini includes the inhabited islands of Santorini and Therasia, as well as the uninhabited islands of Nea Kameni, Palaia Kameni, Aspronisi and Christiana. The total land area is 90.623 km2 (34.990 sq mi). Santorini is part of the Thira regional unit. The island was the site of one of the largest volcanic eruptions in recorded history: the Minoan eruption (sometimes called the Thera eruption), which occurred about 3,600 years ago at the height of the Minoan civilization. The eruption left a large caldera surrounded by volcanic ash deposits hundreds of metres deep. It is the most active volcanic centre in the South Aegean Volcanic Arc, though what remains today is chiefly a water-filled caldera. The volcanic arc is approximately long and wide. The region first became volcanically active around 3–4 million years ago, though volcanism on Thera began around 2 million years ago with the extrusion of dacitic lavas from vents around Akrotiri. Names Santorini was named by the Latin Empire in the thirteenth century, and is a reference to Saint Irene, from the name of the old cathedral in the village of Perissa – the name Santorini is a contraction of the name Santa Irini. Before then, it was known as Kallístē (, "the most beautiful one"), Strongýlē (, "the circular one"), or Thēra. The name Thera was revived in the nineteenth century as the official name of the island and its main city, but the colloquial name Santorini is still in popular use. History Minoan Akrotiri Excavations starting in 1967 at the Akrotiri site under the late Professor Spyridon Marinatos have made Thera the best-known Minoan site outside Crete, homeland of the culture. The island was not known as Thera at this time. Only the southern tip of a large town has been uncovered, yet it has revealed complexes of multi-level buildings, streets, and squares with remains of walls standing as high