In the landscape of the words that describe urban ecosystems, both the terms “metropolis” and “network” occupy a particular place. Dense networks help cities distinguish themselves, whilst metropolises, to exist at national and international levels, encourage the creation of global networks—from high-speed travel by ground or air, to intermodal platforms, ports or hubs, just to mention transportation. As concepts that fluctuate in their meanings and framework, they require to, as the historian Bernard Lepetit (1996: 10–11) argues, “escape the two symmetrical risks of opacifying complexification and blurring of the subject”. We will here focus our efforts on defining the French network metropolis, while exposing the specific characteristics built over the long term.