Rumble is an ambient notification platform to help you learn the locations of invisible urban infrastructures. Some example infrastructures you might want to learn are: subway lines, free WiFi hotspots, public restrooms, and so on. Android-based software monitors your location in the background; when you are near a resource you wanted to know about, a wearable peripheral device vibrates unobtrusively. If you decide you want to learn more about a certain feature, you can press the wearable against your head and hear information via a bone-conduction driver. The work's motivation is to help people optimize their everyday urban experience.