Montjuïc Communications Tower

Stand on the wide stone plaza and look up. A white shape leans out against the sky. It looks less like a building and more like a figure caught in motion. The wind moves across the open ground of the hill, and somewhere behind you a bus engine idles. The light here is broad and clear, and the white surface of the tower takes on the colour of the hour. At midday it looks almost silver. In the late afternoon it turns faintly gold.

This is the Montjuïc Communications Tower. Locals often call it the Calatrava Tower, after its designer, the Valencian architect and engineer Santiago Calatrava. It stands on Montjuïc, the hill that rises above the port, on the edge of the Olympic area. From up here, the land falls away toward the flat plain to the south-west. That plain holds the dense streets of L'Hospitalet de Llobregat, the industrial zone near the port, and the long line of the coast.

The tower exists because of one event — the 1992 Summer Olympic Games. The national telephone company, Telefónica, needed a way to send television and radio signals from the venues to the rest of the world. Billions of people would watch. So the company commissioned a tower that could carry the equipment. But the organisers also wanted something more than a mast. They wanted a shape that people would remember long after the athletes had gone home.

Calatrava answered with a single tilted column. It rises from a broad base and leans at a strong angle. Near the top, a curved ring holds the antennas, like a hand holding something out in front of it. Many people see an athlete lifting the Olympic torch. Others see a kneeling figure making an offering. Calatrava often worked from studies of the human body, and you can sense that here — the tower has a posture, not just a form.

Now look at the base. Here is a detail many visitors walk straight past. The lower part is covered in small broken pieces of white ceramic tile. In Catalan, this technique is called trencadís — a mosaic made from fragments. It is the same method Antoni Gaudí used on his rooftops and benches across the city a century earlier. So this late twentieth century tower carries a quiet greeting to Barcelona's older architecture, right at the level of your eyes.

The second surprise is about time. The tower is often described as a giant sundial. The angle of the column is said to follow the tilt of the sun's path, and its shadow moves across the plaza through the day. Whether you read the hour from it is another matter. But if you stay here for a while, watch the shadow. It sweeps slowly over the stone and the grass, like the hand of a very large, very patient clock.

Think about the engineering problem behind that lean. A straight mast carries its weight straight down. A tilted mast wants to fall over. Calatrava balanced the forward lean of the column with the mass of the base and the shape of the structure below it. This is a theme in much of his work — bridges and towers that seem to defy their own weight. The effect from the ground is calm, even light. The forces underneath are anything but.

The tower does not stand alone. Turn slowly and you will see the other buildings of the Olympic ring. There is the long, low dome of the Palau Sant Jordi, the indoor arena designed by the Japanese architect Arata Isozaki. There is the Olympic Stadium, an older building rebuilt and enlarged for the Games. Between them runs a wide terrace of paving, water and trees. The tower acts as a vertical mark among these broad, horizontal forms.

For Barcelona, the 1992 Games were more than a sporting event. The city used them to rebuild itself. Old industrial waterfront became beaches. New roads circled the city. Montjuïc, long a hill of gardens, a castle and the buildings of an earlier international exhibition, became a sports park as well. This tower was part of that change. It was a technical object, but it was also a message — that the city wanted to look forward.

You cannot go inside the tower. It is a working piece of communications equipment, not an observation deck. That is part of its character. Its job is done in the air above you, in the signals that pass through the antennas. What it offers the visitor is the view of it — from below, from the side, from far away. On a clear day you can pick it out from many parts of the city and from the plain below the hill.

If you walk around the base, the shape changes with every few steps. From one side, the column looks almost straight and thin. From another, the lean becomes dramatic, and the ring at the top seems to float. Try to find the angle where the tower looks most like a figure. Then find the angle where it looks most like a machine. Both are true, and the space between them is where the design lives.

Listen, too. Up here the sounds are different from the streets below. You may hear the wind in the pine trees on the slopes, the voices of joggers and cyclists, a school group crossing the plaza. On event days, the noise of a concert crowd or a match can roll across from the stadium. At quieter times the plaza feels wide and open, and the white tower stands over it in near silence.

Before you leave, take one last look at the white tiles at the base, then let your eyes climb the column to the ring at the top. A structure built to carry television pictures of a few summer weeks has become a permanent part of the skyline. As you walk away, glance back once or twice. Notice how the tower keeps its lean, and how its shadow has moved a little further across the stone since you arrived.