Video security is becoming more and more important today. CCTV (closed circuit television), after broadcast television, is currently migrating from analogue to digital. At the same time, electronics have rapidly progressed in miniaturizing components and standardization initiatives have became popular in the IT world. Due to these innovations, it is now possible to deploy easily and rapidly CCTV in site for permanent or temporary uses. Examples of challenging surveillance applications are monitoring metro stations, detection of loitering or abandoned objects, etc. This chapter describes a practical implementation of a distributed surveillance system with emphasis on video transmission issues (acquisition, visualisation) and image processing necessary for useful event detection. The requirements for these systems are to be easy to use, robust and flexible. Our goals are to obtain efficiently implemented systems that can meet these strong industrial requirements. A computer cluster based approach with network connections is the innovative solution proposed. The main advantage of this approach is its flexibility. Since mobile objects are important in videosurveillance, these systems will include image analysis tools such as segmentation and object tracking. First we present the typical requirements of such a system besides the typical robustness of the analysis (e.g. low false alarm rate and low missed detection rate). We consider issues like the facility to deploy and administer network-connected real-time multicameras, with reusable modular and generic technologies. Then we analyze how to cope with the needs to integrate a solution with state-of-the-art technologies. As an answer we then propose a global system architecture and we describe its main features to explain each underlying module. To illustrate the applicability of the proposed system architecture in real case studies, we develop some scenarios of deployment for indoors or outdoors applications.