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 17km long. Along the way, were ritual waystations, and statues of members of the Branchidae family, male and female, as well as animal figures. Some of these statues, dating to the 6th century BC are now in the British Museum, taken by Charles Newton in the 19th century.

Greek and Roman authors laboured to refer the name Didyma to "twin" temples - not a feature of the site - or to temples of the twins, Apollo and Artemis, whose own cult center at Didyma was only recently established, or whether, as Wilamowitz suggested there is a connection to Cybele Dindymene, "Cybele of Mount Dindymon", is mooted. Recent excavations by the German team of archaeologists have uncovered a major sanctuary dedicated to Artemis, with the key ritual focus being water.

The sixth-century Didymaion, dedicated to Apollo, enclosed its smaller predecessor, which archaeologists have identified. Its treasury was enriched by gifts from Croesus.