Didyma (Didim in Turkish), a resort town quickly becoming overcrowded, was an important sacred site connected to Miletus by a sacred road lined with statues (currently under excavation). The temple of Apollo is here, as well as Altınkum and other beaches, which are increasingly frequented by Brits who have bought real estate in the area.
Didyma is famous for its magnificent Temple of Apollo. As grand in scale as the Parthenon—measuring 623 feet by 167 feet—the temple has 124 well-preserved columns, some still supporting their architraves. Started in 300 BC and under construction for nearly five centuries, the temple was never completed, and some of the columns remain unfluted. The oracle here rivaled the one at Delphi, and beneath the courtyard is a network of underground corridors used by temple priests for their oracular consultations. The corridor walls would throw the oracle's voice into deep and ghostly echoes, which the priests would interpret. The tradition of seeking
advice from a sacred oracle here probably started long before the arrival of the Greeks, who in all likelihood converted an older Anatolian cult based at the site into their own religion. The Greek oracle had a good track record, and at the birth of Alexander the Great (356 BC) predicted that he would be victorious over the Persians, that his general Seleucus would later become king, and that Trajan would become an emperor.
Around AD 385, the popularity of the oracle dwindled with the rise of Christianity. The temple was later excavated by French and German archaeologists, and its statues are long gone, hauled back to England by Sir Charles Newton in 1858. Fragments of bas-reliefs on display by the entrance to the site include a gigantic head of Medusa (twin of the one in Istanbul's Underground cistern, across from Hagia Sophia) and a small statue of Poseidon and his wife, Amphitrite. You can rent a combined Miletus and Didyma audio guide for 15 TL.