The analysis of Large Complex Critial Infrastructures (LCCIs) can be carried out at different levels. The basic level is provided by the analysis of their topological structure which can be carried out on basic (sharable and unrestricted) structural data. In fact, LCCIs can be mapped onto complex graphs which can be analysed by methods recently developed in Graph Theory. These analyses might provide interesting insights on the network's properties, particularly on their "structural vulnerability" and be the starting point for the definition of dynamical model of the network's functioning to be used for the study of more complex properties, such as, for instance, LCCI interdependency.