Church of Hosios David

The lane climbs steeply here. Cobbles and worn steps rise between low houses, and the noise of the lower city falls away behind you. Somewhere a cat crosses a whitewashed wall. Then a small brick church appears behind a gate, plain and modest, almost easy to walk past. This is Hosios David, in the upper town of Thessaloniki. From the outside it looks like a village chapel. Inside, it holds one of the oldest and most moving mosaics in the Christian world.

The building began life as the main church of a monastery known as the Latomou Monastery. Scholars generally date it to the late fifth or early sixth century. That makes it far older than most churches you will see on any trip through Europe. Thessaloniki was then one of the great cities of the Eastern Roman Empire, the empire later historians call Byzantine. Its rulers spoke Greek, governed from Constantinople, and filled their cities with churches.

Look at the shape of the building as you approach. It feels oddly short, as if something is missing. Something is. Archaeologists believe the church was once larger and more symmetrical, and that its western part was lost over the centuries. What stands today is only a portion of the original plan. So the room you enter is a fragment. Keep that in mind... because the treasure inside survived against long odds.

Step inside and let your eyes adjust. The interior is small and dim, and the light is soft. Turn toward the curved wall at the east end, the apse, where the altar would stand. There, set in tiny cubes of coloured glass and stone, is the mosaic. It is not large. Many visitors are surprised by how intimate it is. You can stand close enough to see individual tesserae, the small square pieces that make up the image.

At the centre sits Christ. But this is not the bearded, stern figure of later Byzantine art. Here he is young and beardless, almost gentle. He sits on a rainbow inside a circle of light, the shape art historians call a mandorla, an almond-shaped halo. His right hand is raised. In his left he holds an open scroll. Around him, half-emerging from the light, are four winged creatures — a man, a lion, an ox and an eagle.

Those four creatures come from the Bible's visions of heaven. Christian tradition later linked them to the four evangelists, the authors of the Gospels. The scene draws on the visions of the prophets, especially Ezekiel, who described a figure of glory above living creatures. On either side, two figures watch the vision. They are usually identified as prophets, and one of them seems to recoil in awe. Below, a river runs across the bottom of the scene, with fish and an older male figure who may represent the river itself.

Now for the story the monastery told about this image. Legend has it that a princess named Theodora, the daughter of a pagan emperor, secretly became a Christian. She had the church built, so the tale goes, disguised as a bathhouse. When she feared discovery, she ordered the mosaic hidden behind an ox hide and a layer of mortar. Historians treat this as folklore. But it is a good tale, and it was told here for centuries.

The legend has a second chapter. According to a later monastic account, a monk from Egypt prayed for years to see Christ in his true form. One day, during a storm or an earthquake, the covering fell away. The mosaic appeared before him, and he died in joy on the spot. Again, this is a pious story, not documented history. Yet it shows how deeply people loved this image, and how its hiding and revealing became part of its meaning.

The real history includes a hiding of its own. After the Ottoman conquest of Thessaloniki in the fifteenth century, the church was converted into a mosque, as many churches in the city were. Islamic practice avoids figurative images in places of prayer, so the mosaic was covered with plaster. It stayed hidden for centuries. In the early twentieth century, after the building returned to use as a church, the plaster was removed. The young Christ looked out once more.

And the name? Hosios David means Saint David, or more precisely the holy David. The dedication refers to a local holy man of the sixth century, often called David of Thessaloniki. Tradition says he lived for years in an almond tree near the city walls, praying and fasting. The church took his name later, long after it was built. So the building carries two layers of memory: the early monastery, and a hermit in a tree.

Before you leave, look at the side walls. You may notice faded fragments of wall paintings, much later than the mosaic. These are frescoes, painted on wet plaster, and they are usually dated to the twelfth century. Scenes from the life of Christ survive only in patches. Colours have softened to ochre, rose and grey. Next to the shining glass of the apse, they look quiet and worn — a reminder of how many hands decorated this room.

The church is part of a group of early Christian and Byzantine monuments in Thessaloniki listed together by UNESCO as World Heritage. Many of those monuments are larger and better known, like the great basilicas in the lower city. This one is the smallest of the group you are likely to visit. Its size is part of its charm. You can take it in with one slow look, and then look again.

When you step back outside, notice the view down over the rooftops toward the sea. The upper town survived fires that destroyed much of the lower city, and its lanes still keep an older scale. Listen for the bells, the scooters, the neighbours talking across balconies. Take one last look at the plain brick walls. Behind them, a young Christ on a rainbow is still watching, as he has for some fifteen hundred years.