International audienceEuropean cities can be conceived as forming a system of well interconnected cities since many centuries. The peculiarities of their hierarchical functional organization and territorial patterns have been the subject of numerous analyzes. The purpose of this paper is to detail a few contributions from the science of complex systems to formalize this knowledge. This includes representing the metropolization process occurring within a system of cities with the help of scaling laws and network analysis. We define here the metropolization process, not at the local level of one metropolitan area, but at a macro-geographical level, as the ability of larger cities to capture at first the activities related to innovation waves ...