"So is that Gelsenkirchen now or is it still Essen?" This is a question frequently heard on the area’s former mining tips. Looking at the unending urban landscape, it is easy to grasp what is meant by the term "Ruhr Metropolis". The Schurenbach mining tip (Schurenbachhalde) in Altenessen is one of the many renaturalised tailings piles. What was left over after mining processes as "tailings" was piled up here and the pile was later greened. And the Schurenbach tip was ultimately one of those to be later given an artistic treatment: in 1998 the star American sculptor Richard Serra erected a 15 metre steel slab on the summit of the tip.