We design and implement an Android application, Sensorem, for efficient retrieval and visualization of wireless sensor network (WSN) data. In light of data distribution and visualization being important developmental keystones of smart cities, we seek to enhance sensor data accessibility by developing a user-friendly mobile application (Sensorem) for meaningful visualization of sensor data, targeted at maintenance personnel. Sensor selection can be made with reference to geographical location through an embedded Google Map fragment, as well as a sensor list with sensors in order of WSN node ID. Sensor data is presented through interactive graphs, and graph overlaying functions are offered for easy comparison of data trends. We also employ a Bayesian prefetch algorithm and caching mechanisms to minimize sensor data access latency, such that the app system is able to cope with network and back-end bottlenecks.