Didyma (/ˈdɪdɪmə/; Ancient Greek: Δίδυμα) was an ancient Greek sanctuary on the coast of Ionia. It contained temples for the twins Apollo and Artemis. The oracle of Apollo was situated within the world’s greatest temple for this deity, the Didymaion. In Greek didyma means “twin”, but the Greeks who sought a “twin” at Didyma ignored the Carian origin of the name.
Didyma was first mentioned among the Greeks in the Homeric Hymn to Apollo. Its establishment preceded literacy and even the Hellenic colonization of Ionia. Mythic genealogies of the origins of the Branchidae line of priests, designed to capture the origins of Didyma as a Hellenic tradition, date to the Hellenistic period.
The ruins of Didyma are located a short distance to the northwest of modern Didim in Aydin Province, Turkey, whose name is derived from the ruins. It sits on a headland that in antiquity formed the Posideium Peninsula, but which silt from the Meander River has since connected more thoroughly to the mainland.
Didyma was the largest and most significant sanctuary on the territory of the great classical city Miletus. To approach it, visitors would follow the Sacred Way to Didyma, about 17 km long. Along this route were ritual waystations, and statues of male and female members of the Branchidae family, as well as animal figures. Some of these statues, dating to the 6th century BC, are now in the British Museum, taken by the British archaeologist Charles Newton in the 19th century.