Banya Bashi Mosque

Listen first. Trams grind and clang along the boulevard, and car horns rise and fade. Under all of that there is something softer: water. You cannot see it yet, but warm mineral springs run beneath your feet here. On a cold morning, the air near this corner can carry a faint smell of minerals. That warmth underground is the reason this mosque stands exactly where it does.

You are standing in front of Banya Bashi Mosque, in the old heart of Sofia, Bulgaria's capital. Look at the walls. They are built in bands of pale stone and red brick, laid in neat horizontal stripes. Above them sits a single wide dome, low and heavy, like a lid set carefully over the prayer hall. Beside it rises one slender minaret, the tower from which the call to prayer is sung. The whole building looks calm and compact.

Now for the name. Banya Bashi comes from Turkish, and it is usually explained as meaning something like the place of the baths, or many baths. That is not poetry. It is a description of the location. For centuries, people came to this part of Sofia to bathe in the hot springs. The mosque was built right beside them, so worship and washing shared the same ground.

The mosque dates from the sixteenth century, and it was completed in the 1560s. At that time, Sofia was part of the Ottoman Empire. That empire was ruled from Istanbul, and for hundreds of years it controlled much of southeastern Europe. Ottoman Sofia was a busy trading town, and mosques, baths, inns and markets filled its centre. Most of those buildings are gone today. This one has survived.

Here is the first surprise. The design is traditionally attributed to Mimar Sinan. Sinan was the chief architect of the Ottoman court, and he is the most celebrated builder in the empire's history. He designed the great Süleymaniye Mosque in Istanbul. Historians still discuss how directly he worked on smaller provincial projects like this one. But the attribution has stayed with the building for a very long time, and the clean, balanced shape fits his classical style.

Look again at that single dome. In Ottoman architecture, the dome was the main idea of the building. It creates one open space underneath, without a forest of columns blocking the view. Worshippers inside can stand in long, unbroken rows facing Mecca. Around the base of the dome, small windows let in light. The effect inside is spacious and quiet, even though the street outside is loud.

The second surprise is in the ground itself. The springs here are warm, and the mosque sits almost on top of them. In past decades, visitors noticed steam rising from vents near the walls on cold days. Builders in the sixteenth century did not see hot water as a problem. They saw it as an advantage. Water matters in Islamic worship, because believers wash before prayer. Here, warm water was close at hand.

Today, this is the only mosque in Sofia that still serves as a working place of worship. Once there were many in the city. After Bulgaria became independent from Ottoman rule in the late nineteenth century, most were closed, rebuilt, or demolished. Banya Bashi stayed open. Bulgaria's Muslim community, which includes Bulgarian Turks, Pomaks and Roma, still gathers here. On Fridays, the midday prayer can bring crowds that spill out onto the pavement.

Now turn slowly and look around this square. Within a few minutes' walk you can see a Catholic cathedral, an Orthodox church, a large synagogue, and this mosque. Locals sometimes call this area the Square of Religious Tolerance. It is not a monument. It is simply the shape of the neighbourhood. Different faiths have shared these few streets for a long time, and you can see all of them in one short walk.

Just next to the mosque stands a large, pale building with decorated tiles and arches. That is the old Central Mineral Baths, built in the early twentieth century over the same springs. Today it houses the Museum of the History of Sofia. Behind it, you will usually find people at public taps, filling plastic bottles with warm mineral water. They bring empty containers and wait their turn. It is one of the most ordinary, and most local, scenes in the city.

Across the boulevard, you may notice the covered Central Market Hall. Under your feet, and around this whole area, lie the remains of Serdica. Serdica was the Roman city that existed here long before Sofia had its modern name. Excavations nearby have uncovered streets and building foundations. So this one corner holds several layers at once: Roman stone below, Ottoman brick above, and modern trams running past.

If you would like to go inside, remember that this is an active mosque, not a museum. Visitors are generally welcome outside prayer times. You will need to take off your shoes at the entrance. Dress modestly, with shoulders and knees covered. Women are usually asked to cover their hair, so a scarf is useful. Speak quietly, and avoid walking in front of anyone who is praying.

Before you move on, stand still for one more moment. Look up at the line where the dome meets the sky, and the minaret rising beside it. Listen to the trams again, and think of the warm water moving quietly below the pavement. People have come to this spot to wash, to pray and to trade for more than four hundred years. As you walk away, you might pass the taps where someone is filling a bottle. They are part of the same old habit.