CopenHill, or Amager Bakke in Danish, is a unique waste-to-energy plant located in Copenhagen, Denmark. The WTE plant is set up in a 462, 848-square-foot area and is touted as the cleanest waste-to-energy plant of the world. The roof of the structure is converted into a ski slope, making it an urban mountaineering spot. The structure is also the world’s tallest climbing building.