Big Piano is a non realized project, designed for documenta 5 Kassel 1972.
As an urban musical instrument in shape of a stair leading to a platform it was planned to be installed at Friedrichsplatz in Kassel. The steps of the stair are producing sounds, corresponding to chromatic scales, when stepped on. While visitors moving up and down the stair, they are producing random tone sequences, which are audible in the city center. As a signifficant element a cloud appears several times a day, hiding the viewing plattform on top oft he stair.