In 1961, future West German chancellor Willy Brandt declared: “The sky above the Ruhr must be blue once more.” His words were greeted with what sounded like applause but was actually his audience falling off their chairs. Because the Ruhrpott, or Ruhrgebiet, an agglomeration of industrial cities that includes Gelsenkirchen (where England will play their opening match of the European Championship this summer), Dortmund (which hosts group matches as well as a semi-final), Essen and Duisburg was a place where the chimneys of the coal, iron and steel industries poked up above the smog like candles on a giant grey birthday cake. You were more likely to slip in unicorn droppings than breathe clean air in the Ruhrpott.