If the undulations, loops and dizzy heights of a roller coaster are a little too much for you, you can take them at your own speed, on foot, in Hamburg-based design duo Heike Mutter and Ulrich Genth's new architectural sculpture, Tiger & Turtle - Magic Mountain overlooking the Rhine in Duisburg, Germany.
This 249-stepped, 45m high pedestrian roller-coaster sits on top of a man-made mountain of zinc from a nearby metal works, covered with a coating of grass. "There is so much heavy metal in the hill," says Ulrich Genth, "one used to joke that we could get all the power for our project out of the hill by just pouring acid on it."
The artists say the piece "subtly and ironically plays with the dialectic of promise and disappointment, mobility and standstill. The thing only looks fast from far away, but then it is a struggle to climb it with one's own feet and then even more frustrating when the impassable loop is encountered, confronting the walker with the absurd comicality of the limiting experience of the speed of walking." The title refers, so Genth explains, to the "paradox of Achilles and turtle, so, on one hand, to the turtle as a symbol of slowness and, on the other hand, to the tiger as symbol of capitalism. It reminds us a little of Olafur Eliasson's Umschreibung (2004) in Munich - a staircase which literally leads back to where you started.