Ancient Thera (Greek: Αρχαία Θήρα) is an antique city on a ridge of the steep, 360 m high Messavouno mountain on the Greek island of Santorini. It was named after the mythical ruler of the island, Theras, and was inhabited from the 9th century BC until 726 AD. Starting in 1895, Friedrich Hiller von Gaertringen systematically investigated the city until 1904. Later excavations by N. Zapheiropoulos between 1961 and 1982, under the auspices of the Archaeological Society of Athens, unearthed the city’s necropolis in Sellada. Findings from these excavations are on exhibit at the archaeological museum in Fira. Excavation work was again taken up between 1990 and 1994 under the leadership of Wolfram Hoepfner of the Free University of Berlin and resulted in a more precise understanding of the history of the southern Aegean.
Ancient Thera is today open to the public and can be reached on a winding road that starts at Kamari or several footpaths from both sides of the mountain.