The 21th Century is characterized by an accelerated process of urbanization, which bred two immediate consequences: First, generates an impact on quality of life that allows individuals to have greater access to services and the full benefits of the cities, and secondly, the disputes for the urban area control increase between the State and an several illegal armed actors. In this respect, the present article focus in determine the strategic character of the contemporary cities for criminal structures, due to their characteristics such as density and concentrations of population, capital accumulation, conditions of underground, the organizational possibilities and the new communication technologies. First a general diagnosis will be set up of the criminal situation of the cities such as Medellin and Buenaventura and the criminal control over legal, informal, and illegal activities take place within them. Second makes reference about the growing capabilities in terms of soldiers, organization, weapons, territorial control of the criminal structures. And third refers to the strategic alliances between criminality and insurgency, in order to show the constraints on Nation-State over the effective urban territorial control.