Saint-Séverin, Paris

Step off the narrow street and the noise drops away at once. Outside, there are the voices of waiters calling from Greek restaurants, the clink of plates, and the scuffle of feet on old paving. Inside, the air is cool and smells faintly of stone and candle wax. Your eyes need a moment. The light here is low and coloured, and it falls across tall grey pillars that seem to rise without effort toward the vault.

This is the Church of Saint-Séverin, in the heart of the Latin Quarter, on the left bank of the Seine. It sits only a few minutes' walk from Notre-Dame, yet many visitors pass it without stopping. The streets around it are tight and crooked, so you never see the whole building at once. You catch it in pieces instead. You see a tower above the rooftops, a row of gargoyles, or a pointed window between two shopfronts.

A church has stood on this ground for a very long time. Its story begins with a hermit named Séverin, a holy man who lived near this spot in the early Middle Ages. Much of what people tell about him comes from tradition rather than firm records, so treat the details gently. What is clear is that a place of prayer grew here and was rebuilt several times. The building around you is the result of many generations of work.

The oldest visible parts date from the thirteenth century. Look at the lower levels of the bell tower, near the western end, and you will see simpler, heavier Gothic forms. But most of what surrounds you was built later, in the fifteenth century and the early sixteenth century. That later style is called Flamboyant Gothic. The name comes from the French word for flame, because the stone tracery in the windows curves and flickers like tongues of fire.

Now walk toward the far end of the church, behind the main altar. This is where Saint-Séverin keeps its greatest surprise. The church has a double ambulatory — two curving aisles that wrap around the choir, one inside the other. Walking through them feels less like walking through a building and more like walking through a forest of stone. The pillars branch at the top into ribs, and the ribs spread across the ceiling like the fronds of palm trees.

In the middle of this forest stands one pillar that is different from all the others. Its shaft twists in a spiral, as if someone had wrung the stone like wet cloth. Stand in front of it for a moment. Follow the spiral upward with your eyes, and then watch how the ribs fan out from its top in every direction. Many visitors call it the palm tree pillar. Artists and writers have admired it for generations, and it is easy to see why.

Around the ambulatory, look up at the windows of the small chapels. Here comes the second surprise. These windows are not medieval at all. They are modern abstract stained glass, created in the twentieth century by the French painter Jean Bazaine. There are no saints or kings in them. Instead you see pools of deep blue, red, and gold, shapes that suggest water, fire, and light. The windows are linked to the sacraments of the Church.

The contrast is the point. On one side you have fifteenth-century stone, carved with precise geometry. On the other you have bold modern colour that follows no traditional picture. Somehow the two work together. On a bright day, the coloured light from these windows moves slowly across the pillars and the floor. Come back at a different hour and the whole mood of the space changes. The stone becomes warmer, then cooler, then warm again.

The older windows higher in the nave carry their own history. Some of the glass there is very old, and it shows the stiff, upright figures that medieval glaziers favoured. Others were added or repaired in later centuries. If you scan along the upper windows, you can see the difference in colour and style from one panel to the next. It is a reminder that this church was never finished in one go. It was always being repaired, extended, and changed.

Step back outside and walk around the building if you can. Along the south side there is a small garden enclosed by an arcaded gallery. This was once a charnel house, a place where bones from the crowded parish cemetery were stored. In medieval Paris, burial grounds filled up quickly, and old remains were moved to make room. Today the space is quiet and green. It is one of the very few galleries of this kind still standing in the city.

There is a famous story attached to the old cemetery. According to a popular tale, a pioneering surgical operation was performed here in the fifteenth century on a condemned man who agreed to the risk in exchange for his freedom. The story is told often, but the details vary from one version to the next, so hold it lightly. Whether every detail is true or not, it says something real about this neighbourhood. This was a quarter of scholars, students, and doctors, close to the old university.

As you circle the outside, look up at the roofline. Gargoyles lean out from the walls, their mouths open to throw rainwater clear of the stone. Some are worn smooth by centuries of weather. Others are sharper and clearly later replacements. Listen too. The church tower holds bells, and one of them is said to be among the oldest in Paris. If you are lucky enough to hear them ring, you are hearing a sound this street has known for centuries.

Before you leave, stand for a moment in the little lane by the west front. Around you are the crowded restaurants, the souvenir shops, and the smell of grilled meat drifting from the doorways. Above you rises the same stone that medieval Parisians looked up at. The two worlds sit side by side without trouble. When you walk away toward the river, look back once over your shoulder. The tower will slip behind the rooftops again... and the forest of stone will still be waiting inside.