Nowadays in France, urban leftovers (wastelands, voids, abandoned or neglected spaces) are perceived negatively by the collective imagination, however this has not always been the case. We propose, via a combination of economics and urban planning, a reinterpretation of Albert Lévy’s concept of the three ages of urbanism (1998) on the mutations of the French city throughout History. The aim of this paper is to show that, as of the 1990/2000s, the evolution of perceptions and the re-appropriation of urban leftovers through informal networks of actors rely on new values. This set of values characterise a new emerging social and economic model breaking with the crisis of the production-driven model. We show that these values suggest a new urban model in which urban leftover spaces regain a certain status as urban fallows in town planning strategies, a notion which we conceptualize as a potential for experimentation and adaptation for a resilient urban model. While being markers of the history of cities, signs of past crises and ruptures, urban leftovers are rarely highlighted in the chronology of urban practices and forms. Therein lies the originality of this paper. Furthermore, although Albert Lévy’s model of the three ages of urbanism (1998) is originally based on a reading of the mutations of the French city, its scope is wider as it features a Western understanding of cities which has been shaped over the years by European models as well as the North American model. These characteristics make it an exploitable model for other cities that are experimenting with their urban leftover spaces.