From above

I'm the last to arrive at the clubhouse of the German Alpine Club. The world's largest mountaineering association has a branch here in Duisburg in western-central Germany. Today I'm doing a tour with seven amateur climbers through the climbing park in the so-called Landschaftspark, or landscape park, in Duisburg-Nord, a former ironworks factory that has been converted into a recreational district.

We take the via ferrata - that is, we don't climb directly to the top. Instead, it's like scaling a mountain. Up, then down, the sideways, then up again - and secured with a cable the whole time.

The others are clearly better prepared than I am. Thomas and Stefan have spread harnesses, karabiners and helmets out on a table. "We're not really professional, but we've gone climbing quite often," explain the brothers from Mülheim an der Ruhr.

They've come with a friend to do some training for a tour of the Zugspitze in southernmost Germany, the tallest peak in Germany. I, however, am climbing for the first time, and don't yet know what I'm in for. Most of the others have brought their own equipment along. I'll be borrowing the necessary gear from the Alpine Club.

More than 450 routes

Horst and Sonja Neuendorf from Duisburg's Alpine Cub are leading our tour. Although both are most likely retired, they look pretty fit. I ask Horst how long he has been climbing. "For more than 30 years," he replies. It shows.

Horst gives me my gear: a helmet, a harness - which I step into like a pair of pants - and two short ropes with three karabiners on it. He shows us the most important knots, the overhand knot and the anchor knot. We attach the karabiners to the harness, our safeguard against a fall.

The climbing park is located in the bunkers that were part of the old steelworks. These are huge concrete containers, about 40 meters long (130 feet), 15 meters wide, and 12 meters high, and were once used to store coal and iron ore. It's possible to climb on these vertical concrete walls. They look pretty high, I think to myself.

Horst helped build the climbing area. "When we got the land here in the early 90s, the steel plant had been shut down for several years. Everything was overgrown with plants. That was a lot of work," he says.

Now there are more than 450 climbing routes with nine different levels of difficulty, and more are being added regularly

Touching the sky

We go inside one of the bunkers. A cable is stretched taut and anchored to the concrete wall about half a meter from the floor. This is our practice area, where Horst shows us how to scale the wall. Hold on to the cable, fasten the two karabiners and use your feet to find tiny footholds or small ledges. It looks simple, but it's tough on the arms.

Then things get serious when we start scaling the wall. Hannah, who's training with her father for a climbing holiday in the Alps, stands in front of me. "Do you think it will work with your shoes?" she asks, pointing to my sneakers. "It definitely won't be a problem," I reply. But I'm not so sure.

Nothing can go wrong. I'm doubly secured, but I still have a slightly queasy feeling in my stomach. From below, the wall doesn't look so high, but from above, things look a bit more dangerous.

Horst reads my mind. "Absolutely nothing can happen," he assures me. "Just don't look down."

Staring at the wall, I continue climbing with sweaty hands. Loosen the first karabiner, then re-hook, then the second karabiner, and so on. I had planned to take some photos while climbing, but I don't dare let go of the rope to get my camera out.

My arms start to hurt, and then my feet. Hannah was right; my shoes are not at all suitable for climbing. The soles don't have enough grip and I have to be careful that I don't slip on the smooth concrete. Only small sections of the wall offer traction. At some point my toes start to feel numb.

Revival with a new purpose

After a while I arrive at the top of the 12-meter wall. About half a meter wide, you can walk on the wall albeit with an uneasy feeling. The view here is sensational, stretches far beyond the Ruhr region, all the way to the Rhine. It's amazingly green for an industrial area. Old furnaces and chimneys rise up into the sky. A wind turbine spins in the distance.

The Landschaftspark Duisburg-Nord is an example of structural change in the Ruhr region, Germany's traditional center of heavy industry. Iron ore was smelted here until 1985. These days, concerts, sporting events and exhibition take place here instead. The old gasometer is now filled with water, and you can even go diving in it.

There is always something going on; music echoes from a festival at the foot of the furnaces.

Balancing act

But there's hardly any time to enjoy the view. All the others have arrived at the top and we have to keep moving. At the next station I get dizzy. Two ropes are stretched between the 12-meter walls and, beneath them, the abyss. We need to hook ourselves to one of the cables, while balancing ourselves on another.

We file along, one after the other, so that the ropes don't swing too much. First Horst, then Hannah. Both get to the other side fairly quickly; then it's my turn. I hook myself to the rope and advance slowly, step by step, over the precipice. The rope swings because the wind is gusting quite strongly up here. Nevertheless, I make it across.

Meanwhile, I've gotten quite used to the altitude. I don't mind looking down so much anymore. Only my shoes remain a problem. I can't get much grip, so I have to rely on my arm muscles. I am especially sore when I get down to the bottom again two hours later.

All the same, climbing here has been great fun. Perhaps I'll try it in on a real mountain next time.