During 2007-2009, a consultative call for urban plans for Greater Paris, dubbed the Consultation Internationale du Grand Paris, triggered stimulating debate over the crucial issues facing major metropolises. Various approaches attempted to come to terms with the globality of the “metapolis” and potential ways of dealing with it. Architects played a privileged part in this broad analytical process, notably questioning the role of their profession in building metropolises faced with ever-denser flows, constant obsolescence, and the difficult task of making architectural intervention intelligible. In the most “operational” phase of implementation, designs for Greater Paris forthrightly explored the issue of conceiving metropolitan projects as a new, collective way of conceptualizing and acting upon a city. This article discusses the imposing corpus of work generated by the consultative process, using that event to question the fabric of metropolitan projects in large contemporary cities. One of the emerging paradigms addressed here is urban polycentrality, understood in a polysemic way. The change in the meaning of “project” triggered by the metropolitan dialectic then leads to an examination of two experiments that came in the wake of the Consultation Internationale du Grand Paris, namely the Grand Paris Express project and the development of the Saclay area.