Casa da Música

Start with your feet. The ground around you is not flat. The pale stone plaza rises and dips in gentle waves, like a beach where the sand has hardened into rock. Skateboarders know this. On many afternoons you will hear the click and roll of wheels moving across these slopes. Then lift your eyes. A white, angular block sits in the middle of the plaza and seems to lean in every direction at once. It looks less like a building and more like a cut stone.

This is Casa da Música, the House of Music, Porto's main concert hall. It was designed by the Dutch architect Rem Koolhaas and his firm, the Office for Metropolitan Architecture, usually shortened to OMA. The building opened in 2005. It was first planned for 2001, the year Porto shared the title of European Capital of Culture. Construction took several more years. Many people in the city remember the long wait, and the arguments about how much it cost.

Here is the first surprise. The shape you are looking at did not begin as a concert hall at all. Koolhaas has explained that the design grew out of an earlier, unbuilt project for a private house in the Netherlands. In that house, a family would gather in one central room for living. For Porto, the team scaled the idea up dramatically. The central room became the main auditorium. The smaller rooms around it became foyers, rehearsal spaces, stairs and bars.

Take a moment to look at the surface of the walls. They are white concrete, cast in large planes that meet at sharp angles. No two faces seem to point the same way. In bright sun, each face catches the light differently, so the building looks striped with shadow. On a grey Porto morning, it turns soft and chalky. Walk slowly around the outside. The building will change shape with almost every step you take.

Now turn around and look across the road. In the middle of the large roundabout behind you rises a tall column with sculptures at the top. This roundabout is known locally as the Rotunda da Boavista. The monument remembers the Peninsular War, the struggle against Napoleon's armies in the early nineteenth century. Look closely at the very top. A lion stands over an eagle. The lion stands for Portugal and its British allies. The eagle stands for Napoleon's France.

The contrast is worth a pause. On one side of the street, a column of stone and bronze celebrates an old victory. On the other side stands a building that refuses straight lines entirely. Between them flows ordinary Porto traffic... buses, taxis, people heading home. Boavista is a newer part of the city than the old riverside. It feels wider and more open. The House of Music was placed here partly to give this area a new centre of life.

If you go inside, the heart of the building is the main hall, called Sala Suggia. It is named after Guilhermina Suggia, a cellist born in Portugal who became one of the best-known performers of her instrument in the early twentieth century. The hall follows a classic shoebox shape — long, tall and narrow. Many acousticians consider that shape one of the most reliable for orchestral sound. So inside this unusual building sits a very traditional idea.

Here is the second surprise. Most concert halls are sealed boxes, closed off from the outside world. Sala Suggia has huge windows at both ends. The glass is corrugated, folded into waves, which helps to control the sound. During daytime concerts and rehearsals, the audience can see the city outside while the music plays. The walls inside are covered in wood panels, decorated with a pattern of gold that looks like an enlarged wood grain. Under the stage lights, it glows warmly.

The building is home to several resident groups. The best known is the city's symphony orchestra, which carries the name of the house itself. There is also a contemporary music ensemble and a baroque orchestra that plays early music. Programmes here range widely. On one evening you might hear a full symphony. On another, you might hear jazz, fado, electronic music or a children's concert. The building was designed to hold many kinds of music, not just one.

As you move through the interior, notice how the circulation works. Stairs and escalators wind around the main hall, rather than lining up in neat corridors. You climb, turn, and suddenly a window frames a slice of the city. Some rooms have their own strong personality. One room is lined with traditional blue and white tiles, called azulejos, the painted ceramic tiles you see on church fronts and houses all over Portugal. Another space near the top is covered in a bold black and white pattern.

Guided tours run through the building regularly, and they are the easiest way to see rooms that are closed during performances. A guide can usually take you into the main hall when no concert is on. That is a rare chance to stand on the floor of a working concert hall in silence. Listen to how your footsteps sound. Clap once, softly, and notice how the sound carries. Check at the front desk for tours in your language.

It is fair to say that not everyone loved this building at first. Some residents found it strange, even cold. Others questioned the delays and the expense. Over the years, though, it has become part of the daily life of the city. Students wait for friends on the plaza. Families sit on the sloping stone in the evening. The metro station nearby even carries its name. For many people in Porto, it is now simply a place they meet.

Before you leave, find a spot on the plaza a little way back from the entrance. Look at the whole shape once more. Notice the dark openings cut into the white walls, where the windows of the main hall face the street. If a concert is about to begin, you may see people gathering inside the glass. Then let your eyes move back to the column and its lion across the road. Two very different centuries face each other here — and the city keeps moving between them.