We propose a method that can visualize the spatiotemporal measurements originating from a sensor network. Each sensor records a sequence of measurements and the accumulation of these measurements is of central interest. Importantly, the sensor can associate with the attribute that contains a hierarchy on its values. Our method, called Time Ring Maps, can 1) capture the sequence and distribution of the measurements, 2) allow the user to compare temporal patterns between sensors, and 3) display the temporal patterns at different hierarchy levels when users zoom the background map. The applicability of the Time Ring Maps is demonstrated on real world data from traffic network monitoring.