Rheinturm

Stand at the base of the tower and tilt your head back. The concrete shaft rises in one smooth, pale column, and the wind off the Rhine pushes against your jacket. Somewhere above you, small round lights are blinking in a steady rhythm. Most people walk past them without a second thought. By the end of this walk, you will be able to read them... and they will tell you exactly what time it is.

This is the Rheinturm, the Rhine Tower of Düsseldorf. It is a telecommunications tower, built to carry radio, television and telephone signals across the region. At around 240 metres, it is the tallest structure in the city. It went up at the end of the 1970s and opened in the early 1980s. Since then it has become the single shape most people use to picture Düsseldorf's skyline.

The design came from the German architect Harald Deilmann. Look at the overall form. A slim concrete shaft tapers gently as it climbs. Near the top it swells into a wide, layered head, the cabin that holds the viewing platform and the restaurant. Above that, a thinner mast continues upward and carries the antennas. It is a classic form for towers of this era across Germany. Here, though, it sits right on the riverbank, so the reflection often doubles it in the water.

Now, back to those lights. Running up the side of the shaft is a column of round portholes, lit from within. This is a light sculpture by the artist Horst H. Baumann, called the Lichtzeitpegel, which translates roughly as the light time level. It is not decoration alone. It is a working clock. Many sources describe it as the largest digital clock in the world. Here is how to read it.

Read the clock from top to bottom. The highest group of lights shows the hours. The middle group shows the minutes. The lowest group shows the seconds. Each group has two parts — one for the tens and one for the single units. You count how many lights are on in each part. Between the groups, a few lights in a different colour act as separators, like the colons on a digital watch.

So, a quick example. Suppose the top section shows one light in the tens and four in the units. That means fourteen hours — two in the afternoon. Then do the same for the minutes below. Watch the bottom section for a moment. You will see the seconds tick upward, one light at a time, until the tens light changes. Once you see it, you cannot unsee it. Locals sometimes test their visitors with exactly this puzzle.

Let your eyes drift to the surroundings. The tower stands at the edge of the MedienHafen, the Media Harbour. This was once a working river port, full of warehouses, cranes and goods trains. In the late twentieth century, the city reshaped it into a district of offices, studios, restaurants and hotels. Old harbour basins remain, and some historic warehouse buildings were kept and converted. New architecture grew up beside them.

The most famous of these new buildings are close by — three twisting, curving structures designed by the Canadian-American architect Frank Gehry. Together they are known as the Neuer Zollhof. One is clad in white plaster, one in shining metal, one in red-brown brick. Their windows seem to push out of the walls at odd angles. From the right spot near the tower, you can frame the Gehry buildings and the Rheinturm in a single view, old port water in the foreground.

Right next to the tower, you will also find the Landtag, the state parliament of North Rhine-Westphalia. Düsseldorf is the capital of this state, the most populous in Germany. The parliament building is low, round and modern, a clear contrast to the vertical tower beside it. So, in a few steps, you move from broadcasting to politics to media and architecture. That mix says a lot about how this part of the city works today.

If you go up, a fast lift carries you to the upper levels in well under a minute. Your ears may pop on the way. The observation level has windows that lean outward at an angle. Many visitors find it a little unnerving at first. Then they rest their hands or their forehead against the glass and look straight down. The river, the roads and the harbour basins spread out below like a detailed map.

Above the viewing level sits a restaurant that slowly rotates. The movement is gentle, so you barely feel it. Over the length of a meal, the whole panorama passes by your table. On one side, the old town and its church spires. On another, the long curve of the Rhine and its bridges. On a clear day, the view runs far across the flat lowlands of the Lower Rhine. You can follow barges for kilometres as they move along the water.

The tower also changes with the hour of the day. In the morning light, the concrete looks almost white. At dusk, the clock lights grow stronger against the darkening sky. On some evenings and special occasions, the head of the tower is lit in colour. From the promenade along the river, many people stop here simply to watch the city lights come on, one district after another.

The Rhine promenade itself is worth your time. It runs from here north toward the old town, a wide walkway beside the water. Joggers, cyclists and families share the path. In good weather, people sit on the steps facing the river with a drink or an ice cream. Barges and passenger ships slide past. The sound here is a mix of wind, water, gulls and distant traffic on the bridges.

Before you leave, look up one more time. Find the top group of lights and count. Then the middle. Then watch the bottom group climb, second by second. That small rhythm has been running above the river for decades, quietly telling the time to anyone who knows the trick. Now you are one of them. As you walk away along the water, glance back now and then... and read the hour from the tower.