Hagia Sophia, İznik

Listen first. Traffic hums at the crossroads, a tea glass clinks somewhere nearby, and then the ground seems to drop away. To reach the doors of this building, you walk down, not up. The old church sits lower than the modern street, as if the town has slowly risen around it. That small descent is the first lesson this place teaches. You are stepping onto ground that belongs to another age, the level where people walked many centuries ago.

You are standing in İznik, a quiet lakeside town in northwestern Turkey. Long before it had that name, it was Nicaea, an important city of the Roman and then Byzantine world. Byzantium was the eastern half of the Roman Empire, which lasted for about a thousand years after Rome itself fell. Its capital was Constantinople, today's Istanbul. Nicaea was close enough to that capital to matter, and far enough away to have a life of its own.

Look at the street plan around you. The town still follows a grid laid out in Roman times. Two main streets cross near the centre, and each one runs toward a gate in the old city walls. Hagia Sophia stands right beside this meeting point. The name is Greek, and it means Holy Wisdom. It is the same dedication as the great church in Istanbul, but this building is smaller, plainer, and in many ways more intimate.

The story of the building is a story of rebuilding. Scholars generally date the first church here to the early Byzantine period, roughly the sixth century. Earthquakes are common in this region, and the church suffered serious damage over time. Much of what you see today comes from later reconstruction, often dated to around the eleventh century. So this is not one building from one moment. It is layer upon layer of repair, each generation patching what the last one left behind.

Now comes the event that gives this church its place in world history. In 787, bishops from across the Christian world gathered here for a church council. It became known as the Second Council of Nicaea. For decades, the empire had argued bitterly over religious images, called icons. One side believed that painted images of Christ and the saints were holy. The other side believed they were idols and should be destroyed. This dispute is known as Iconoclasm, which means the breaking of images.

The council that met inside these walls decided in favour of the icons. It declared that honouring sacred images was proper, as long as worship itself was given to God alone. That decision shaped the look of Eastern Christianity for more than a thousand years. Every gold icon in a Greek, Russian, or Georgian church today stands, in part, on the ruling made here. It is a surprising thought, in a building this modest.

Many visitors confuse this council with a more famous one. The First Council of Nicaea took place in 325, and it produced the Nicene Creed, a statement of faith still recited in churches around the world. That earlier council was held in this city, but not in this building. Most historians believe it met at an imperial palace, whose exact location is still debated. So the church you are standing in belongs to the second council, not the first.

In 1331, Nicaea fell to the early Ottoman state under Orhan, the second Ottoman ruler. The city became one of the first important Ottoman centres, before Bursa and later Istanbul. The church was converted into a mosque, and it became known as the Orhan Mosque. A minaret was added, the slender tower from which the call to prayer is given. Tradition also credits the great Ottoman architect Sinan with restoration work here in the sixteenth century.

The building's role kept changing. After centuries of decline and further damage, it served for many decades of the twentieth century as a museum. In 2011, it was opened again for Muslim prayer. Today it is an active mosque. That means carpets on the floor, shoes left at the entrance, and a quieter mood during prayer times. Visitors are welcome outside of prayers, and modest dress is expected, with women usually covering their hair.

Once inside, let your eyes adjust. The space is long rather than tall, a basilica plan with a central hall leading toward a curved apse at the far end. In that apse, look for the stepped rows of stone seating. These tiers are called a synthronon, and they held the clergy during services. Imagine the bishops of 787 sitting in places very much like these, listening, arguing, and finally voting on the fate of the icons.

Search the walls for traces of colour. A faded fresco survives, showing Christ between the Virgin Mary and John the Baptist. This grouping is called a Deësis, a Greek word for prayer or supplication. The figures are worn and partly lost, but they are still there. There is a quiet irony in this. A council that defended sacred images met here, and some of those images outlasted empires, earthquakes, and centuries of change.

Look down as well. In places, fragments of older floor decoration have been uncovered, with patterns of coloured stone. Outside, walk around the exterior and study the walls. You can see brick laid in bands with stone, a typical Byzantine method that helped buildings flex during earthquakes. Some sections look clean and regular, while others are rough and mended. Each change in texture marks a different moment of repair, and you can read the building's long survival in its masonry.

When you climb back up to street level, notice how ordinary the surroundings feel. Tea houses, shopfronts, and passing cars sit right beside a building where the course of a world religion was settled. İznik is like that. Its Roman gates still stand, its lake still shines to the west, and its tile workshops still continue the town's famous Ottoman ceramic craft. History here is not behind glass. It sits in the middle of daily life.

Before you move on, pause at the top of the steps and look back down at the old walls. The ground you are standing on now is centuries younger than the floor below. Somewhere in that small drop in height is the distance between 787 and today. Take a breath of the lake air, listen to the street noise return, and carry that quiet picture of the sunken church with you as you walk into the town.