The purpose of this paper is to illustrate an optimal design procedure for security fixed communication networks that, thanks to Genetic Algorithms (GAs), is capable of reaching the desired goal of preserving the architecture of buildings characterized by installation constrains, such as the historical ones, and of reducing the cost of installation, ensuring a high level of benefit/cost ratio. This technique has been used in the design of security systems of historical sites such as Vatican City State, Senate of Italian Republic, museums, churches, etc. in Italy giving excellent results.