In this presentation, a tool that has been developed to optimally site sensors in order protect a specific facility, a region in a city, or a military base from a chemical, biological, or radiological agent attack is described. The tool utilizes the Quick Urban & Industrial Complex (QUIC) dispersion modeling system in order to rapidly compute tens of thousands of plumes to use in siting the sensors. In this talk, we describe the concept of "protecting" a built-up site, how the modeling system works, the input requirements, and output products. Validation of the modeling system against experimental data will also be presented, along with a discussion on the model limitations.