Hagia Sophia, Trabzon

Stand still for a moment and listen. Wind comes up the slope from the Black Sea, and gulls call somewhere below. Under your feet, the paving is warm or damp, depending on the day. In front of you is a compact church of pale, honey-coloured stone. Its dome sits on a tall drum, and the whole building looks small next to the open sky above the coast.

This is the Hagia Sophia of Trabzon. The name means Holy Wisdom, the same dedication as the great church in Istanbul. This building is much smaller, and that is part of its charm. It was not built to impress a capital of millions. It was built for a small, proud Christian state on the edge of the medieval world, a state that survived for more than two and a half centuries.

That state was the Empire of Trebizond. Trebizond is the old Greek name for Trabzon. The empire was founded in 1204, the same year crusaders sacked Constantinople. Two brothers of the Komnenos family, a dynasty of former Byzantine emperors, took control of this coast. They had help from a neighbour, the Georgian Queen Tamar, who was their relative. From this strip of land between mountains and sea, they ruled as emperors.

The church was built in the thirteenth century, most likely under Emperor Manuel the First, who ruled around the middle of that century. Historians link it to him because of its style and its imperial emblem. It stood outside the old walled city, on this hill to the west. In those days the sea came closer to the slope than it does today. Ships arriving from the west would have seen the dome first.

Now look at the shape of the building. The plan is a cross inside a square, a classic Byzantine layout. A central dome rises over the crossing, and four arms reach out beneath it. But walk around the outside and you will notice something unusual. Three large porches open to the north, south and west. Each porch is almost like a small building of its own, attached to the main body.

Go to the south porch, the side facing the sea. Above the arch runs a long band of carved stone. It tells the story of Genesis, the first book of the Bible. You can follow Adam and Eve, the forbidden fruit, and the expulsion from paradise. The carving has weathered, and some faces are worn smooth. Still, the figures are clear enough to follow from left to right, like a strip of pictures.

Near that frieze, look for a carved eagle with a single head. Many visitors expect the double-headed eagle of Byzantium. This one is different. The single-headed eagle was linked to the Komnenos rulers of Trebizond. It is a small detail, but it marks the church as the work of this local dynasty, not of distant Constantinople. It is a signature cut into the stone.

Here is something many people miss. Some decoration on the porches does not look Byzantine at all. You can see geometric patterns and interlaced designs that recall the art of the Seljuk Turks, who ruled much of Anatolia, the Asian part of Turkey, at that time. Other features point toward Georgian and Armenian building traditions. This church was built at a crossroads, and its stones show that. Craftsmen and ideas moved across these borders, even between rival powers.

In 1461, the Ottoman sultan Mehmed the Second took Trabzon. He was the same ruler who had captured Constantinople eight years earlier. The Empire of Trebizond ended, and with it the last independent Byzantine state. Later, the church became a mosque. The frescoes inside were covered over with plaster. Over the following centuries, the building also served other purposes in difficult times, including use during the First World War.

That plaster turned out to be a gift. In the late 1950s and early 1960s, a team from the University of Edinburgh, led by the art historian David Talbot Rice, worked here with Turkish authorities. They carefully removed later layers and found paintings that had been hidden for centuries. The colours had survived remarkably well. Afterwards, the building opened as a museum, and scholars came to see some of the finest late Byzantine painting anywhere.

In 2013, the building became a mosque again. Today it is a working place of worship, so dress modestly and remove your shoes inside. During prayer times, the frescoes in the main hall may be covered by curtains or screens. If they are visible, look up. Painted saints, angels and scenes from the life of Christ fill the vaults. The paintings in the porches outside are often easier to see.

Before you leave, turn toward the tall square tower that stands apart, a short walk from the church. This is the bell tower. It was added later, in the fifteenth century, when the empire was near its end. Its separate position is worth a moment of thought. In many Byzantine churches, the bells and the sanctuary were close together. Here the tower stands on its own, like a watchman over the grounds.

The gardens around you are part of the experience. Local families walk here, and some visitors sit on benches facing the sea. In the late afternoon, the sun drops in the west and the stone turns a deeper gold. The carved frieze on the south side catches the low light, and the worn figures gain a little more shadow and depth.

So take one last look. A small domed church, three deep porches, a carved story of the first humans, and a single-headed eagle. It has been a cathedral, a mosque, a museum, and a mosque again. It has outlived the empire that built it by more than five centuries. As you walk back toward the city, listen again for the gulls, and notice the sea below the hill.