During the Hellenistic period the oracle of Apollo at Didyma was the most renowned in the Greek world, surpassing even the famed oracle of the god at Delphi.
Excavations have revealed that the earliest Greek construction at Didyma was an alter dating from the eighth century B.C, which a century or so later was enclosed in a naiskos and peripteral colonnade. The colossal archaic Temple of Apollo erected in the decade 560 - 550 B.C., having King Croesus as its principal benefactor.
The archaic temple was destroyed by Xerxes in 494 BC. when he sacked Miletus. But it was rebuilt early in the Hellenistic era by King Seleucus I of Syria. The architects of the second temple were Paeonius of Ephesus and Daphnis of Miletus.