Spiegel:
Some of the art at this year's Documenta has escaped the confines of the exhibition halls and intervened in Kassel's public spaces -- like Kirill Preobrazhenskiy's "Tram 4 Inner Voice Radio," a sound installation played on a busy public transportation route.
This strategy has been tried before, though. From 1982 through 1987, Joseph Beuys came to Kassel and planted 7,000 trees alongside slabs of stone as part of an installation called "7,000 Oaks," for Documenta 7. Visitors still snap photos of the trees, which have become an internationally renowned work of art. Kassel residents rarely take a second glance.