Artists have reimagined a power pylon as an electrified dancing silhouette for a summer exhibition in Germany's Ruhr region. Through an optical illusion the art work "Zauberlehrling" (sorcerer's apprentice), by the art collective Inges Idee, seems to dance as the viewer approaches. The piece is part of the second edition of the Emscherkunst exhibition series, which bills itself as the world's largest outdoor art show. The event stretches out over a 50-square-meter (538-square-foot) plot along the banks of the Emscher River and will include works by big-name artists, including Ai Weiwei, Tomás Saraceno and Daniel Buren. In the 1970s, the Emscher River was one of Germany's most polluted. Following extensive renaturalization procedures, the area is now one of the region's biggest attractions.