An augmented reality musical instrument and mobile app that allows users to encode pavement and stones with sound and music. The instrument conceals your smart phone as it detects preset patterns in the street using computer vision. Those patterns act as triggers for musical experiences. Users can explore the city as they look for triggers left behind by street composers. This turns a familiar city into an infinitely programmable musical environment waiting to be explored. Much of this project was inspired by going to the beach as a kid and watching a man with a metal detector scan the sand looking for treasure.