Didyma was an ancient Greek sanctuary on the coast of Ionia in the domain of the famous city of Miletus. Apollo was the main deity of the sanctuary of Didyma, also called Didymaion. But it was home to both of the temples dedicated to the twins Apollo and Artemis. Other deities were also honoured within the sanctuary. The Didymaion was well renowned in antiquity because of its famed oracle. This oracle of Apollo was situated within what was, and is, one of the world's greatest temples to Apollo. The remains of this Hellenistic temple belong to the best preserved temples of classical antiquity. Besides this temple other buildings existed within the sanctuary which have been rediscovered recently; a Greek theatre and the foundations of the above-mentioned Hellenistic temple of Artemis, to name but two.

Miletus was an ancient Greek city on the western coast of Anatolia, near the mouth of the Maeander River in ancient Ionia. Its ruins are located near the modern village of Balat in Aydın Province, Turkey. Before the Persian rule that started in the 6th century BC, Miletus was considered among the greatest and wealthiest of Greek cities.