Hagios Demetrios (Church of St. Demetrios), Thessaloniki (must see)

The Church of Saint Demetrios is dedicated to Saint Demetrios, the city’s patron saint and a Roman martyr of the early 4th century. According to tradition, Demetrios was a high-ranking Roman official or military commander who openly professed Christianity during the reign of Galerius. Over time, Demetrios came to be venerated as a military saint and protector of Thessaloniki, believed to have defended the city during its many sieges.

A shrine was first established over the place of his martyrdom, and in the early 5th century it was replaced by a three-aisled basilica. After a major fire in the 7th century, the church was rebuilt as a five-aisled basilica, largely defining the structure that survives today. The present building dates primarily to this reconstruction, though it has undergone repeated restoration following fires, earthquakes, and periods of conversion, including use as a mosque during the Ottoman era.

Architecturally, Hagios Demetrios is one of the largest basilicas in Greece, notable for its scale and relatively restrained exterior. As you enter the church, the interior opens into a broad forest of columns that divide the space into five parallel aisles. The church’s most celebrated artistic treasures are its Byzantine mosaics, dating from the 5th to the 9th centuries. To see them, move slowly along the central nave and into the side aisles, keeping your eyes at upper wall level, above the columns.

Several of the best-preserved mosaics are located along the north and south interior walls, especially near the transept and the area just before the sanctuary. Look for panels showing Saint Demetrios standing frontally, often flanked by clergy, civic officials, or children presenting offerings. Only nine mosaics survived the Great Fire of 1917.

After viewing the mosaics, proceed toward the sanctuary and look for the entrance leading downward. Beneath the sanctuary lies the crypt, traditionally identified as the site of Demetrios’ imprisonment and death. Today, it functions as a museum space, where you can see archaeological remains of the Roman bath complex. Each year on October 26, the feast day of Saint Demetrios, the church becomes the focal point of major religious celebrations.