Tetrahedron in Bottrop

Construction was carried out by Rüter GmbH from Dortmund, and the Emscherblick slag heap event was officially opened on the Day of German Unity in 1995.

At the top of the tetrahedron, the Düsseldorf artist Jürgen LIT Fischer designed the impressive light sculpture called "Fractal".

The stairs and platforms are suspended movably in the structure on steel cables, which means that there can be slight fluctuations in strong winds.

This independent design was part of a series of activities in which other IBA Emscher Park landmarks, such as the Brockenscheidt slag heap of the Waltrop colliery with the track tower by artist Jan Bormann, were also redesigned by citizens.

In 2008, the Regionalverband Ruhr (RVR) requested an expert opinion because the citizens' unauthorised artistic activities, including the aliens on the Tetraeder, were not legally permitted.