Surrounded by gray walls made of concrete for many years. In the Swiss town of Lenzburg, however, the situation is somewhat different: from fall 2012 to spring 2014, well-known Swiss street artists designed 4661 square meters of wall space at the new local penitentiary. They were free to draw or spray paint anything they wanted. In more than 25,000 hours of work, a total of 1,400 spray cans and 200 liters of paint were used to turn a barren, cold...