Eons ago, this place was a wilderness. A jungle of plants foreign to us, big as trees, on the shore of a shallow lagoon. The world to which the place belonged, however, has long perished; its organic remains have been transformed into coal.
Fast forward to the 19th century: Coal became the fuel for the industrialisation of Germany. Consequently, a coal mine has been established in this place.  In the following decades, hundreds of thousands tons of coal have been mined here. Eventually, the extracted void collapsed (a mining subsidence, in technical terms), and a lake formed by ground water; subsequently, mining has been abandoned.
So, the place has been left to itself - barren, abused, its soil contaminated. Nowadays, it is wedged between a highway and a busy railroad line. But Nature reclaimed it all the same. Brambles and stinging nettles, japanese knotweed and goldenrod, hawthorns and elders, dogwood and poplars and many others have made it a wilderness again.