The project adds quite a bit of musical flavour to the city by turning a set of stairs of the Pedestrian Underpass (on ul. Rayko Daskalov 51) into a giant piano. Each step elicits a sound from a piano key. The piano stairs are activated by a software that plays audio files when a sensor is triggered.
Globally the initiative has involved millions of people, and change in urban environments can already be found in Stockholm, Milan, San Francisco, Athens, and Sao Paolo.