Tetrahedron in Bottrop in Bottrop, Germany

Sitting atop the highest point in the region, the Tetrahedron in Bottrop is an esoteric piece of modern art that allows visitors to climb inside to take in the surrounding landscape. 

The giant, skeletal piece of geometry stands on a quartet of concrete pillars which are embedded into an old mining pile that towers above the city of Bottrop. The three-dimensional pyramid was erected to reflect the modernization and changes in the surrounding area, giving visitors a chance to take in the area for miles around. From tip to tip to tip the massive pyramid measures almost 200 feet, which, in addition to the 30 foot pillars makes the tetrahedron a shining metal jewel which can be seen from miles away.  

A strangely erratic staircase winds from the ground on up to a viewing platform in the center of the structure. The whole piece strangely resembles a jungle gym for mathematicians.