Saint Joseph's Church, Le Havre

Step inside, and the first thing you notice is the light. It does not fall from one direction. It surrounds you. Thousands of small squares of coloured glass climb the walls above your head, and the grey concrete around them glows amber, rose and deep blue. The floor is plain and the air is cool. If the day is bright outside, the colours move slowly across the stone as clouds pass over the harbour.

This is Saint Joseph's Church, and it is unlike most churches you will ever visit. There are no carved saints along the walls, no gilded altarpiece and no painted ceiling. Instead, there is concrete, glass and an enormous column of open space rising straight above the altar. People sometimes expect a cold building. Most people leave with the opposite impression.

To understand why the church looks like this, we have to go back to September 1944. In the final stage of the Second World War, Allied bombing raids struck Le Havre, which German forces were holding. The centre of the city was almost completely destroyed. Around five thousand civilians are commonly said to have died. The old church of Saint Joseph stood in this district, and it was lost with everything around it.

After the war, the city needed to be rebuilt almost from nothing. The task went to the architect Auguste Perret and his team. Perret was already known as a pioneer of reinforced concrete, which is concrete strengthened with steel bars inside. He believed this material could be honest and beautiful at the same time. He planned a new city of straight streets, repeated grids and buildings that showed their own structure openly, without decoration hiding it.

Saint Joseph's Church became the spiritual centre of that plan. Construction ran through the 1950s. Perret died in 1954, before the building was finished, and his collaborators completed the work after him. So, in a sense, you are standing inside his final major project. It was also designed as a memorial. Many people in Le Havre still see the church as a place that remembers the civilians killed in the bombing.

Now look up — slowly. Above the altar, the tower rises as one hollow, octagonal shaft. An octagon is a shape with eight sides. From the outside, the tower reaches a little over one hundred metres, and from inside you can see far up into it. Coloured glass lines the walls all the way to the top. The effect feels a little like standing at the bottom of a tall lantern.

That comparison is deliberate. From the sea, the tower is one of the first things sailors see as they approach the port. It works as a landmark, almost a lighthouse for the city. At night, when the tower is lit, it stands above the low rooftops of the rebuilt centre. For a port that lost so much, a tall light that faces the water carries a strong meaning.

The stained glass was created by Marguerite Huré, a French glass artist who worked closely with Perret. Her glass is not a set of pictures. There are no scenes from the Bible here. Instead, she used thousands of small pieces in carefully chosen colours, and the number most often given is more than twelve thousand. The colours are arranged so that the light changes as you move around the space, and as the sun travels across the sky.

Here is something many visitors miss. Try to come back at a different hour. In the morning, the light inside has one character. In the late afternoon, it shifts to another. The same building can feel calm and blue at one moment, and warm and golden a few hours later. The architect did not add colour with paint. He let the sun do that work.

Now bring your eyes back down to the ground. The altar stands in the centre, directly under the tower, and the seating surrounds it on all sides. This was an unusual choice for its time. In most older churches, the altar sits at one far end of a long hall. Here, the plan is close to a square, so the congregation gathers around one central point. Many visitors find this feels more like a meeting than a performance.

Take a moment to look closely at the concrete itself. Perret paid great attention to its surface. Run your eyes along the pillars and walls, and you will see different textures and small changes in tone. He wanted concrete to be treated with the same care as fine stone. This concrete was not meant to be covered up. It was meant to be seen, and touched, and respected.

When you walk back outside, you will notice that the church is part of a larger design. The surrounding streets follow the same ordered grid, and many buildings share the same pale concrete and repeated proportions. In 2005, UNESCO added the rebuilt centre of Le Havre to its World Heritage List. UNESCO described it as an important example of post-war planning and of the use of concrete in architecture. The tower is the vertical centre of that entire composition.

Before you go, stand for a moment near the entrance and look back toward the altar. Notice how quiet it is, even with other visitors around you. Notice the colours on the floor near your feet. As you step out into the streets, look up once more at the tower against the sky. It rose from a city in ruins, and it still keeps watch over the harbour today.