The monuments being gradually brought to light through excavations bear witness to the importance of Thessaly during the first Christian centuries and its prominent role in the evolution of culture in general.
The Christian faith found in Thessaly a most fertile soil and a considerable segment of its population had become Christians already in the first centuries of the Christian era. However, the question of who was the first herald of the new faith still remains a matter of dispute.Possibly it was Herodion, one of the seventy apostles or St. Andrew or even Onesimos, a follower of St. Paul, who is specifically mentioned in St. Paul’s Epistle to Philemon. We lack precise information on Church administration. From the years of Constantine the Great until the first half of the eighth century the province of Thessaly had been subject to eastern Illyricum, under the jurisdictum of the Pope, and especially to the administration of Macedonia that was excercised by the Metropolitan of Salonica, a vicar to the Pope. A considerable number of Early Christian monuments, mainly basilicae, as well as secular monuments, public and private have been preserved within the geographical circuit of present day Thessaly. The most important of them are listed below in counties:
A. County of Trikala: Early Christian basilica at the site Prophetes Elias; basilica (?) in the castle of Trikala; Early Christian basilica (church of the Dormition of the Virgin); Early Christian basilica at the side of the the national road that connects Larissa with Trikala.
B. County of Karditsa: Basilica at the site Chamamia.
C. County of Larissa: Early Christian basilica in the castle of Larissa; Early Christian basilica, unidentified as yet; Early Christian cemetery on the east of the Larissa castle; secular building; cistern; basilica of Elassona; Early Christian basilica of Pyrgeto.
D. County of Magnesia: Seventeen monuments in Nea Anchialos; two in ancient Demetriada; basilica at Achilleio; a considerable number of Early Christian ruins and remnants in the town of Volos and on the islands of Skiathos, Skopelos and Alonnessos.