In the transition of the nineteenth to the twentieth century, coping with the growing industrialization of a new capitalist Lisbon and the concomitant migration of workers into the city, various working-class neighbourhoods, known as “patios” or “villas” emerged, to such an extent that by 1902, an estimate of c.200 existed in various locations of Lisbon. Initially built mostly by private owners, some were erected by industrialists and factory owners to house their workers close to their working places. At the same time, discussions in parliament addressed the issue, proposing forms to involve the state and the municipality in their construction. This movement was accompanied by discussions concerning workers’ welfare, a politically-driven issue for anarchists, Saint-Simonians and Marxists, also discussed by scientists, engineers and physicians as both a question of physical and moral health. By looking at instances of reforms of the (sub)urban landscape associated with the emergence of working-class neighbourhoods, some implemented, others simply imagined, we analyse how fluxes of people, capital and techno-scientific expertise interacted in fostering urban renewal, often informed by Saint-Simonian and republican ideals.