The Tetraeder in Bottrop, Ruhrgebiet area, NRW, Germany

This one maybe not as interesting as some of the others, but i think it still deserves a post.

Its a 50 meter high viewing platform out of steel, that has build on the top of a 65 meter high mining heap (build up from mining from 1969 until 1993). It sits on top of the greened heap as an intended symbol for the change of the ruhrgebiet from mining and heavy industries to .. well, whatever will become of it now.