Thessaloniki is the center of the cult of St. Demetrius, the patron Saint and the Saint of this city, and its magnificent temple Basilica built on the ruins of the baths, where in the year 303 he was in prison, suffered and was buried, the great Martyr Demetrius. Marble walls, mosaic murals, moldings, capitals, etc. from different eras - these are the characteristic features of this unique monument, which was founded in 412-413, eparch Leonty, burned in 1917 and was re-opened after restoration in 1948.

Under the Holy altar of the temple is the place where he died a Saint is an ensemble consisting of a one-aisled Basilica, where he was buried, Saint Demetrius, and a separate semi-circular space with rectangular columns, parapets and columns, surrounded by water tanks. In the tank has a Central marble arch with built-in sink before him, flowing myrrh.

Six small mosaics of the V and VII centuries, not affected by fire, are in the chancel and in the upper part of the West wall of the Church. The mosaics depict St. Demetrius surrounded by children.