Diachronic analysis of social structure in Italian metropolitan areas: a comparative-historical research and open-access database for urban studies (DIAMETROIT).

Urban research has demonstrated the impact of residential location on life chances and opportunities. This perspective highlights how population structure and territorially embedded opportunities and constraints shape life courses, employment, crime and civic participation. Imbalances in social structure may lead to residential segregation, often with adverse consequences for disadvantaged groups. However, prevailing frameworks-largely developed in rental-dominated or ethnicity-focused contexts-tend to treat dimensions such as age and occupation as analytically independent. DIAMETROIT advances a different view: in home-ownership-centered housing regimes, these dimensions are jointly mediated by the intergenerational transmission of property, which structures access to space and opportunities. In Europe, which is traditionally characterized by strong welfare systems, residential segregation is increasing in major urban areas. This trend calls for a shift in analytical focus from metropolitan cores to broader functional urban areas (FUAs), where economic opportunities and structural constraints increasingly operate. Understanding segregation also requires a diachronic perspective that captures long-term transformations. In Italy, however, comprehensive metropolitan analyses on a fine spatial scale remain limited. This gap reflects both technical and institutional constraints: data aggregation at administrative levels, changing census units and limited longitudinal comparability, alongside chronic underfunding and a fragmented research system. At the same time, the Italian case is theoretically consequential: high home ownership rates and a familistic welfare regime mean that housing access is largely mediated through intergenerational transfers, reinforcing the link between demographic and socio-economic segregation. The DIAMETROIT project focuses on two dimensions: generational and socio-professional segregation. Younger cohorts face increasing precarity in labor and housing markets, yet their spatial distribution remains underexplored. Socio-professional segregation, which is central in European debates, is also gaining relevance in Italy amid stagnant wages and rising costs. Rather than treating these as separate processes, we interpret them as interdependent outcomes of housing structures. By developing harmonized, comparable spatial units and integrating demographic and socio-economic data, the project provides new insights into metropolitan inequalities across Italian FUAs.