Byzantine Culture

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Hagios Demetrios, Thessalonica

The great basilica of St Demetrios in Thessalonica, its seventh-century votive mosaics, the miracle collections, the fire of 1917 and the rebuilding — and the cult of the soldier saint.

Thessalonica was the second city of the Byzantine Empire for most of its history, and its patron was a young Roman officer martyred under Galerius at the beginning of the fourth century. The basilica built over the site of his martyrdom became one of the great pilgrimage churches of the Christian east, and its mosaics — particularly a group of seventh-century votive panels — are among the most informative works of art to survive from the empire’s most obscure century.

The church burned almost completely in 1917 and was rebuilt. What is there now is partly reconstruction and partly original, and telling the difference is part of the interest.

Demetrios

The saint’s historical existence is thin. The tradition makes him a Roman officer or a deacon, imprisoned for his faith and killed by spears in the baths of Thessalonica around 306, during the persecution under Galerius. A young Christian named Nestor, whom Demetrios had blessed, killed the emperor’s favourite gladiator Lyaios in the arena and was executed too.

By the fifth century a shrine existed on the site; by the seventh, Demetrios was the city’s protector in a fully military sense, credited with appearing on the walls during sieges. The collections of his miracles, compiled by Archbishop John of Thessalonica in the seventh century and by an anonymous later author, are among the most valuable narrative sources for the period — they describe Avar and Slav sieges, plague, famine and civic politics in circumstantial detail, precisely because the author needed circumstantial detail to make the miracles credible.

Demetrios is a myroblyte saint: his shrine was said to exude fragrant oil, which was collected by pilgrims in small lead or clay flasks. Hundreds of these ampullae survive across the Balkans and beyond, and they map the reach of the cult.

The Building

The church is a five-aisled basilica with a transept — a large, conservative plan of the fifth century, rebuilt after a fire in the 620s, which is when most of the surviving mosaic decoration was installed.

Its size is the first thing to register: this is not a small middle Byzantine church but a late antique basilica on the scale of the great Roman foundations, with rows of columns carrying arcades and galleries above, and a timber roof. Thessalonica in the fifth and sixth centuries was a wealthy imperial city, and the building reflects it. The contrast with the small, intensely decorated churches of later centuries described in Byzantine church architecture is instructive.

Below the church is a crypt, discovered after the 1917 fire, containing the remains of the Roman bath complex where the martyrdom was traditionally located, and a basin associated with the collection of the holy oil.

The Mosaics

The surviving mosaics are votive panels rather than a unified programme — individual images set up by individual donors on the piers flanking the sanctuary, mostly in the seventh century.

They are strange and compelling. The saint stands frontally, a young man in patrician dress with a chlamys and fibula rather than armour, one arm around the shoulder of a donor. In one panel he stands between the bishop and the eparch — the civil governor — of the city, with an inscription thanking him for saving Thessalonica. In another he places his hands on the shoulders of two small children. In another, a mother presents her child.

The style is not classical. The figures are frontal, flat, wide-eyed and static, with no interest in anatomy and a strong sense of ceremonial presence. This is the manner that would later be called Byzantine in the strict sense, and seeing it emerge in datable seventh-century work is one of the reasons Hagios Demetrios matters so much to the history of the medium described in Byzantine mosaics.

Several mosaics were destroyed in the 1917 fire and are known only from photographs and watercolours made before it — a significant loss, since the pre-fire record includes panels of the same group.

The Ottoman Period and the Fire

The church became the Kasımiye mosque in 1493 and remained one for four centuries. The mosaics were plastered over, which preserved them; some were uncovered during nineteenth-century repairs.

On 18 August 1917 a fire broke out in the crowded upper town of Thessalonica and destroyed roughly a third of the city, including the basilica. The roof collapsed, the columns calcined, and much of the decoration was lost.

Reconstruction ran from 1926 to 1949, interrupted by the war. The rebuilt basilica reuses surviving material where possible: original columns and capitals stand alongside replacements, and the distinction is generally visible. The surviving mosaics were consolidated and reinstalled.

Rebuilding a burned monument on this scale raises questions that were argued at the time and have not gone away — whether the result is the fifth-century church, the seventh-century church, or a twentieth-century Greek statement about both. The answer is the third, and the building is no less worth seeing for it.

The Relics

The saint’s relics have their own itinerary. They were removed to Italy at some point in the medieval period and kept at the abbey of San Lorenzo in Campo in the Marches. The main body was returned to Thessalonica in 1978 and the remaining relics in 1980, and they are now in a silver reliquary in the north aisle. Whether these are the relics of the fourth-century martyr is not a question archaeology can settle; what is certain is that they were venerated as such for many centuries in two countries.

The Other Churches of Thessalonica

Hagios Demetrios is one of fifteen Thessalonican monuments on the UNESCO world heritage list, and the city holds the best continuous series of Byzantine churches anywhere outside Istanbul:

  • The Rotunda, a fourth-century imperial structure converted to a church, with late antique mosaics of extraordinary quality in the dome
  • Hagia Sophia, eighth or ninth century, with an Ascension in the dome and an aniconic cross in the apse from the iconoclast period, later overlaid
  • Panagia Chalkeon, dated by inscription to 1028, a textbook cross-in-square in brick
  • Hagios Nikolaos Orphanos and Hagioi Apostoloi, both with major fourteenth-century fresco cycles

Anyone seriously interested in Byzantine art should spend two days in Thessalonica; the sequence of buildings there covers a thousand years with no significant gaps.

What the Miracle Collections Contain

The two Miracles of St Demetrios collections are among the most valuable narrative sources for the seventh century, and the reason is that a miracle story needs circumstantial detail to be believed.

The first collection was compiled by Archbishop John of Thessalonica in the early seventh century; the second by an anonymous author later in the same century. Between them they describe:

  • The Avar and Slav sieges of the city in 586 and the 610s–620s, with details of siege engines, tactics, the conduct of the defence and the negotiations
  • Plague in the city, its course and the civic response
  • Famine, grain shipments and the mechanics of supply
  • The internal politics of the city — disputes between the archbishop, the eparch and the population, and an attempted coup
  • Slav settlement in Macedonia and the relations between the settled groups and the city

Because the author’s purpose is to attribute deliverance to the saint, he describes precisely what was being delivered from, and he assumes an audience who lived through it and would notice errors. Historians of the Balkan seventh century use these texts more than any chronicle.

The saint appears as a young man in patrician dress, on the walls, in dreams, or intervening to redirect a missile — the same figure who appears in the mosaics on the piers of his own church.

The 1917 Fire and the Reconstruction Debate

The fire of 18 August 1917 destroyed roughly a third of Thessalonica, including the basilica, and the decision about what to do next was argued for a decade.

The options were to consolidate the ruin as an archaeological site, to build a modern church on the footprint, or to reconstruct the basilica as it had been. The third was chosen, and work ran from 1926 to 1949.

The reconstruction reused what survived: columns and capitals that had not calcined were re-erected, and the surviving mosaic panels were consolidated and replaced on the piers. Replacements were made where necessary, and the distinction between original and new material is generally visible in the stone.

The criticisms made at the time and since are the standard ones — that the result is a twentieth-century building representing a lost fifth- and seventh-century one, and that the choices about which phase to reconstruct were not neutral. The defence is that the alternative was to lose the most important church in the second city of Byzantium as a functioning building.

What the fire cost is documented: several mosaic panels known from pre-1917 photographs and watercolours no longer exist, and the pre-fire record is therefore primary evidence in its own right.

The Crypt

The crypt, discovered during the post-fire clearance, is frequently skipped and should not be.

It contains the remains of a Roman bath complex — the traditional site of the martyrdom — with a basin and channels associated with the collection of the holy oil, and a substantial display of architectural sculpture, capitals and ambones recovered from the church and from the city.

The arrangement makes the shrine’s mechanics legible: pilgrims descended to the source of the myron, filled ampullae, and took them home. Those lead and clay flasks, found from the Balkans to Britain, are the archaeological trace of the pilgrimage described in relics and pilgrimage.

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