tetrahedron in german bottrop taken on a cloudy summer day. the walkable steel structure built on a mine dump

amazing architect architectural architecture area attractions awesome background beautiful bottrop built cloudy coal construction day design deutschland dump elements engineering european family future futuristic german germany hill industrial industry interesting landmark landscape metal mine mining modern monument non north outdoor places rhinewestphalia ruhrgebiet stairs steel steps structure summer taken technology tetraeder tetrahedron tourist tourists traditional travel triangle trip walkable