St. Mary's Cathedral, Tokyo

Stand still for a moment and look up. Above you, sheets of stainless steel curve and twist into the sky, catching the light like the side of a folded paper boat. On a clear day the metal flashes almost white. Under cloud it turns soft and grey. The street around you is quiet, residential, a little sleepy. And then this shape rises out of it, sharp and silver, like nothing else on the block.

This is Saint Mary's Cathedral, the mother church of the Roman Catholic Archdiocese of Tokyo. It sits in Sekiguchi, in Bunkyo ward, a calm district of schools, gardens and hillside streets. Many visitors come expecting stained glass, pointed arches and old stone. What they find instead is one of the boldest buildings of postwar Japan. It looks more like a sculpture than a church. That surprise is part of the experience.

The cathedral you see today is not the first on this site. An earlier church stood here, a wooden building in the Gothic style, with the familiar pointed shapes of European churches. During the Second World War, the air raids of 1945 destroyed much of Tokyo, and that wooden church was lost in the fire. For years afterwards, the Catholic community of the city worshipped without a proper cathedral. The rebuilding would take time, money, and help from far away.

That help came from Germany. The Catholic Archdiocese of Cologne supported the reconstruction, and the bond between the two churches continues today. Think about the timing for a moment. Both countries were rebuilding from the ruins of the same war. Cologne itself had been heavily bombed. Yet its Catholic community chose to help raise a new cathedral on the other side of the world. It is a quiet story, and many people who walk past the building never hear it.

The architect was Kenzo Tange, one of the most influential Japanese architects of the twentieth century. The cathedral was completed in 1964. That same year, Tokyo hosted the Summer Olympics, and Tange also designed the Yoyogi National Gymnasium, with its sweeping suspended roof. So in a single year, one architect gave the city both a new stadium and a new cathedral. Both buildings use dramatic curves. Both showed the world a confident, modern Japan.

Now look again at the walls. Tange built the cathedral from eight curved shells. Each one is a shape that engineers call a hyperbolic paraboloid. In plain words, it is a surface that curves up in one direction and down in the other, like a saddle or a crisp potato chip. These shells lean against each other and rise towards the sky. Their edges never fully close. Between them, long strips of glass run up the walls and across the top.

Here is the detail most visitors miss. If you could fly above the cathedral, you would see that those strips of glass form a cross. The whole building is a cross when seen from the sky. From the ground, you only catch parts of it — a glass seam here, a sharp angle there. Inside, the cross becomes light. It is a design meant less for the eye of the visitor in the street, and more for the experience of standing beneath it.

The shining outer skin is stainless steel. It covers a structure of reinforced concrete. Over the decades, weather and time took their toll, and the cathedral has undergone major restoration work to repair and renew the metal surface. As you walk around the outside, notice how the panels change colour with the angle of the sun. On one side they glow. On the other they fall into shadow. The building looks different every hour of the day.

When you step inside, the mood changes completely. The bright steel is gone. Instead, you are surrounded by bare, raw concrete, rising high on every side. You can still see the texture of the wooden boards that shaped the concrete when it was poured. The space is tall, dim and very quiet. Your footsteps carry. A cough sounds loud. Many people lower their voices without being asked.

Look upward. The thin lines of daylight from the cross-shaped glass fall down the grey walls. Behind the altar, a tall window lets light pour in from top to bottom. There is very little decoration. No painted ceilings, no crowded statues. The shape of the room and the light coming in do almost all of the work. It feels modern, but also very old — closer to a cave or a mountain valley than to a palace.

The cathedral is also known for its pipe organ, an Italian instrument made by the Mascioni company. The concrete walls give the music a long, rolling echo. If you are lucky enough to visit during a Mass, a recital or a choir rehearsal, stay and listen. Sound in this space does not simply fill the room. It seems to rise up the walls and hang under the roof before it fades.

Before you leave, walk the grounds. To one side stands a tall, slender bell tower, separate from the main building, its narrow form echoing the sharp lines of the cathedral. Elsewhere you will find a replica of the grotto at Lourdes, in France, the place where Catholics believe the Virgin Mary appeared to a young girl in the nineteenth century. Here, local worshippers light candles and pause to pray. It is one of the most personal corners of the site.

Remember, this is a working church, not a museum. People come here to pray, to marry, and to say goodbye. When Kenzo Tange died in 2005, his funeral was held inside the cathedral he had designed four decades earlier. Weddings take place here often, and on some days you may see a bride and her family arranging photographs outside. Move gently, keep your voice low inside, and give space to anyone at prayer.

As you walk back towards the street, turn around one last time. Watch how the steel catches the sky above the rooftops of Sekiguchi. Listen to the neighbourhood — a bicycle bell, children from a nearby school, the hum of the city in the distance. A church that was once destroyed by fire now stands here in metal and light, built with help from a city on the other side of the world. Take that thought with you as you go.