DELIA, a festival of Apollo held every five years at the great panegyris in Delos (Homeric Hymn to Apollo, 147). It included athletic and musical contests, at which the prize was a branch of the sacred palm. This festival was said to have been established by Theseus on his way back from Crete. Its celebration gradually fell into abeyance and was not revived till 426 B.C., when the Athenians purified the island and took so prominent a part in the maintenance of the Delia that it came to be regarded almost as an Athenian festival (Thucydides iii. 104). Ceremonial embassies (θεωρίαι) from all the Greek cities were present.
See G. Gilbert, Deliaca (1869); J. A. Lebègue, Recherches sur Délos (1876); A. Mommsen, Feste der Stadt Athen (1898); E. Pfuhl, De Atheniensium pompis sacris (1900); G. F. Schömann, Griechische Altertümer (4th ed., 1897–1902); P. Stengel, Die griechischen Kultusaltertümer (1898); T. Homolle in Daremberg and Saglio’s Dictionnaire des antiquités.