When we talk about the "Smart City", we often imagine futuristic scenarios involving drones, connected traffic lights, and expensive IoT sensors installed on every lamp post. It is a fascinating vision, but often financially unfeasible for the budgets of small-to-medium Italian Councils. However, there is a network of sensors already capably distributed across the territory, active 24/7 and at zero cost to the Administration: the citizens. Every citizen equipped with a smart