AIT experts have developed novel methods for continuous security monitoring of public spaces by combining features extracted from different sensor modalities. A prototype was tested and evaluated at a public hot spot in Vienna: suspicious or criminal activity was automatically detected by fusing data from visual, acoustic and thermal imaging sensors and applying advanced pattern analysis and classification methods. The system has been piloted over a period of 2 months in real-time operation, and tested on 80 test scenes of criminal activity recorded with actors.