According to tradition the temple of Agios Demetrios was built over the grave of Agios Demetrios and is a five-aisled basilica with a narthex and a transept. The date of its construction is not known to us. In the passage that describes the wonders of Agios Demetrios it is mentioned that the church was built by the eparch Leontios (around 412-413 A.D.), who was cured by the Saint from a very serious illness. Other archaeological and historical indications place the erection of the church a whole century later. In spite of its well-preserved façade it had a very trying past, equal to that of Thessalonica. The church was destroyed in a big fire sometime between 629 and 634 A.D. but it was soon reconstructed by the archbishop and decorated with mosaics. In 1493 it was turned into a mosque by the Ottomans and the elaborate mosaics were covered by a thick coating of plaster. This intervention actually proved to be quite a blessing in the long run because those exquisite works of art, hidden as they were, managed to survive to this day. They were revealed by accident in 1907 during some restoration work, but the temple was once again ruined in the great fire of Thessalonica in 1917.
The restoration began almost at once and was completed in 1952, recovering the churches original shape and giving us a small taste of how imposing the atmosphere of the interior used to be. The most famous church mosaics, placed in the 7th century A.D., survived the second destruction and can be seen on the west side of the temple. They depict Agios Demetrios standing between two children and then the Saint in the company of the eparch and the bishop.
In the south-eastern corner of the temple you will find the chapel of Saint Euthymios with exquisite 13th century wall-paintings and a crypt under the sanctuary where according to tradition, Agios Demetrios was held prisoner and later died a martyr.