Urban vitality is closely related to the built environments such as street architectures in the city. We propose a vitality evaluation system which calculates the amount of human activities under the use of mobile phone signaling Origin-Destination (OD) data. Meanwhile, because of the strong correlation between urban safety and urban vitality, the potential security risks of street architectures of different categories at different moments in a day are able to be appraised by our method. Experiments on the database of the street view images and mobile OD data in Nanjing, China validate the practicality and accuracy of our method. Moreover, we study the distribution of Points of Interest (POI) nearby street architectures of different vitality. A series of heuristic conclusion which will help optimizing the planning of street facilities are drawn from our study.