Thyatira, a titular suffragan see of Sardes in Lydia. According to Stephanus Byzantius, the name was given to the city by Seleucus I Nicator; it is more probable that it is of Lydian origin. A Macedonian colony was established there (Strabo, XIII, 4); several divinities were worshipped there, such as Aesculapius, Bacchus, Artemis, above all Apollo, in whose honor games were instituted. Vespasian began great undertakings at Thyatira; it was visited by Hadrian in the year 123, and by Caracalla in 215. Lydia, the woman converted by St. Paul at Philippi, was from Thyatira (Acts, xvi, 13-15); St. John addressed an epistle to the “angel of the church”, to whom he gives great commendation, but after having criticised a false prophetess (Apoc., ii, 18-29). Paprylus, martyred about the year 250 at Pergamus, venerated October 13, was also from this city; we know from testimony given by St. Epiphanius (Contra hr., LI, 33), that at the beginning of the third century almost all Thyatira was Christian. Among the bishops mentioned by Le Quien (Oriens christianus, I, 875-78), we may note Seras, in 325; Fuscus, at the Council of Ephesus in 431; Diamonius, in 458; Basilius, in 878. The bishopric was suffragan to Sardes as late as the tenth century (Gelzer, “Ungedruckte. Texte der notitire episcopatuum”, 537, 553); it is not known when it disappeared. In the Middle Ages the Turks changed the name of Thyatira to that of Ak-Hissar (the white fortress), which it still bears. It numbers 22,000 inhabitants, 7000 of whom are Greek schismatics, 1000 Armenians and Jews, and 14,000 Mussulmans; it is a caza of the sandjak of Saroukhan and of the vilayet of Smyrna.