Source: (also more pictures there) https://landschaftspark.de/besucherfotos-community. Landschaftspark Duisburg-Nord is an old steelworks plant in the Meiderich district of Duisburg in the Ruhrgebiet area, that has been converted to a recreational area.

Edit: Lets post places as bledposting, that are not reposted every 10mins on reddit, so that people get to know interesting places in europe.