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, and it included temples to both Apollo and his twin sister, Artemis; other deities were also honoured there. Didyma was known in antiquity for its famed oracle of Apollo, situated within the god's temple. The remains of this Hellenistic temple are among the best-preserved from classical antiquity. Other buildings from the sanctuary included a Greek theatre and the Hellenistic temple of Artemis.