The SAFE-CITIES Architecture (SCA) is designed as a stratified environment where each layer addresses its own concern whilst promoting extension, openness, reusability and easy-deployment across pan-EU regions, cities, and urban areas. In particular, the SCA encompasses three distinct layers where each individual layer builds on top of the functionality of each layer: Infrastructure, Back-end Application and Front-End Application. This approach is supplemented the Collaborative Security and Vulnerability Assessment with participation of threats and vulnerability experts, policy makers, urban planners, and end users.