Amazing stairways from The World Geography:
This 21-metre-high (69 ft) sculptural walkway is named Tiger and Turtle – Magic Mountain by Heike Mutter and Ulrich Genth, and is positioned upon a hilltop in Duisburg, Germany. A staircase winds across the surface of the steel structure, which spirals around itself just like the fairground ride. The visitor can climb the art work by foot. Although the course describes a closed loop, it is impossible to accomplish it as the looping emerges to be a physical barrier.
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