The Fun Theory is an initiative supported by Volkswagen, based on the idea that ‘something as simple as fun is the easiest way to change people’s behaviour for the better’. The Fun Factory team set themselves the challenge of getting more people to take the stairs by making it fun to do so. Stairs located next to escalators were transformed into a working piano, with every step playing a note to the Swedish public.

The idea of the Piano Stairs struck a chord (pun intended) with people around the world, with a video of the concept clocking up over 13 million views on YouTube. And if imitation really is the sincerest form of flattery, then the Fun Theory team should have a very healthy ego, with replica Piano Stairs appearing in Auckland, Melbourne, Stockholm, Milan, Istanbul and Colombia.