Surveillance systems provide the capability of collecting authentic and purposeful information and forming appropriate decisions to enhance safety. This paper reviews concisely the historical development and current state of the three different generations of contemporary surveillance systems. Recently, in addition to the employment of the incessantly enlarging variety of sensors, the inclination has been to utilize more intelligence and situation awareness capabilities to assist the human surveillance personnel. The most recent generation is decomposed into multisensor environments, video and audio surveillance, wireless sensor networks, distributed intelligence and awareness, architecture and middleware, and the utilization of mobile robots. The prominent difficulties of the contemporary surveillance systems are highlighted. These challenging dilemmas are composed of the attainment of real-time distributed architecture, awareness and intelligence, existing difficulties in video surveillance, the utilization of wireless networks, the energy efficiency of remote sensors, the location difficulties of surveillance personnel, and scalability difficulties. The paper is concluded with concise summary and the future of surveillance systems for public safety.