Visitors stand beside the installation 'Head On' by Chinese artist Cai Guo-Qiang at an exhibition at the Deutsche Guggenheim in Berlin August 26, 2006. The installation consists of a pack of 99 life-sized wolves, fabricated from painted sheepskins and stuffed with hay and metal wires, barrelling in a continuous stream towards - and into - a constructed glass wall. The exhibition runs from August 26 to October 10, 2006. [Reuters]