At documenta 7 in Kassel in 1982, Joseph Beuys began his work 7000 Eichen – Stadtverwaldung statt Stadtverwaltung, 7,000 oaks, city forestation instead of city administration. He piled 7,000 basalt columns on the Friedrichsplatz. Each tree was planted together with one of the stones. Beuys died in 1986. At documenta 8 in 1987, the last tree was planted next to the first one. Beuys said that planting trees could not be surpassed for Nachhaltigkeit, lasting effect.