Castoria is a Catholic titular see. The original diocese was in Macedonia.
Livy[1] mentions a town near a lake in Orestis, called Celetrum, whose inhabitants surrendered to Sulpitius during the Roman war against Philip V of Macedon (200 B.C.). Procopius[2] relates that Justinian, finding the town of Diocletianopolis ruined by the barbarians, built a city on the lake, of Castoria. Tafel[3] suggests that Celetrum, Diocletianopolis, and Castoria are three successive names of the same place. In any case, Castoria seems to have replaced Celetrum.
There Bohemond camped with his army at Christmas, 1083. The Byzantine chroniclers describe it as a strong fortress. In the tenth century it must have been occupied by the Bulgarians. About 1350 it was given up by the Emperor Joannes Cantacuzene to the King of Serbia, and in 1386 it was captured by the Turks.
As early at least as the reign of Basil II, Castoria was the first suffragan see of the archdiocese of Achrida. Lequien[4] mentions only three bishops: Joasaph in 1564, Hierotheus, who went to Rome about 1650, and Dionysius Mantoucas.
Some ten Latin bishops are known from the thirteenth to the fifteenth centuries.[5]