Bike Hills at the Garden of Remembrance, Dani Karavan, 1999

I don't think that the undulating hills at artist Dani Karavan's Garden of Remembrance in Duisberg were intended as a playscape, but the artist wouldn't mind:

"Generally, my work is created for people to use. My art cannot exist without people. My work is not there to be looked at but to be experienced.”

photos and text from the book 'In Gardens', published by Birkhäuser Basel, 2005.