Grindstone Devotional is an interactive soundwalk of Philadelphia's Tacony neighborhood created by The Mural and The Mint, with members of the community. Go to Torresdale Avenue between Longshore Avenue and Disston Street, launch the app, put on your headphones, put your phone away and start walking the blocks between Longshore and Disston to the park. Each part of the journey has its own distinctive experience. You must be in the appropriate place to experience this app. Continued use of GPS running in the background can dramatically decrease battery life.