DIDYMI or DIDYMA, an ancient sanctuary of Apollo in Asia Minor in the territory of Miletus and on the promontory Poseideion. It was sometimes called Branchidae from the name of its priestly caste which claimed descent from Branchus, a youth beloved by Apollo. As the seat of a famous oracle, the original temple attracted offerings from Pharaoh Necho (in whose army there was a contingent of Milesian mercenaries), and the Lydian Croesus, and was plundered by Darius of Persia. Xerxes finally sacked and burnt it (481 B.c.) and exiled the Branchidae to the far north-east of his empire. The celebrated cult-statue of Apollo by Canachus, familiar to us from reproductions on Milesian coins, was also carried to Persia, there to remain till restored by Seleucus I. in 295, and the oracle ceased to speak for a century and a half. The Milesians were not able to undertake the re building till about 332 B.C., when the oracle revived at the bidding of Alexander. The work proved too costly, and despite a special effort made by the Asian province nearly 400 years later, at the bidding of the emperor Caligula, the structure was never quite finished: but even as it was, Strabo ranked the Didymeum the greatest of Greek temples and Pliny placed it among the four most splendid and second only to the Artemisium at Ephesus. The area covered by the platform measures roughly 36o X i6o feet.
No excavation was attempted till MM. E. Pontremoli and B. Haussoullier were sent out by the French Schools of Rome and Athens in 1895. They cleared the western façade and the pro domos, and discovered inscriptions giving information about other parts which they left still buried. Finally the site was purchased by, and the French rights were ceded to, Dr. Th. Wiegand, the German explorer of Miletus, who in 1905 began a thorough clear ance of what is incomparably the finest temple ruin in Asia Minor.
The temple was a decastyle peripteral structure of the Ionic order, standing on seven steps and possessing double rows of outer columns 6o ft. high, twenty-one in each row on the flanks. It is remarkable not only for its great size, but (inter alia) for (I) the rich ornament of its column bases, which show great variety of design; (2) its various developments of the Ionic capital, e.g., heads of gods, probably of Pergamene art, spring from the "eyes" of the volutes with bulls' heads between them; (3) the massive building two storeys high at least, which served below for prodomos, and above for a dispensary of oracles Xpr)aµoypaxl)ca mentioned in the inscriptions) and a treasury; two flights of stairs called "labyrinths" in the inscriptions, led up to these chambers; (4) the pylon and staircase at the west; (5) the frieze of Medusa heads and foliage. Two outer columns are still erect on the north-east flank, carrying their entablature, and one of the inner order stands on the south-west.
See Dilettanti Society, Ionian Antiquities, ii. (1821) ; C. T. Newton, Hist. of Discoveries, etc. (1862) and Travels in the Levant, ii. (1865) ; O. Rayet and A. Thomas, Milet et le Golfe Latmique (1877) ; E. Pontremoli and B. Haussoullier, Didymes (1904) •