This image was acquired from
wikimedia. It was marked as Public Domain or CC0 and is free to use. To verify, go to the source and check the information there.
Keywords from Image Description:
Bottrop Tetraeder CN. Der Tetraeder auf der Halde Beckstrae in Bottrop vom alpincenter aus gesehen The Tetraeder tetrahedron on the spoil tip Halde Beckstrae in Bottrop North RhineWestphalia Germany seen from the inddor ski resort alpincenter on another spoil tip own kastn Disk Other versions region DENW Photographs by Carschten