This is a book that offers an in-depth interdisciplinary analysis of metropolitan policies on a wide range of issues affecting the economy, democracy, technology, governance, ecology, culture, demography, migration and security. The authors of the large-scale study - Bulgarian and French experts, renowned scholars and unencumbered young minds from a variety of scientific fields - make an effort to make sense of urban development through the prism of sustainable development, putting the conclusions drawn at the service of the city of Sofia. The texts included a look at the classical paradigm of sustainable development, including aspects from the economic, social, environmental spectrum. At the same time, as the most up-to-date studies do, the individual strands are conceptualized in a holistic order, guided by the understanding that it is impossible to implement sectoral policies independently, one by one, without taking into account the others. In the authors' understanding, sustainable urban development can only be achieved through a balance between economic activities that protect natural resources, reflecting the cultural context, strengthening social stability and ensuring citizen participation in the formulation of urban decisions.