Traditional towns in Portugal and Brazil have evolved, since the thirteenth century, a finely tuned coordination between, on the one hand, modular dimensions for street widths and lot sizes, and on the other, a typology of room shapes and distributions within houses. Despite being well documented in urban history, this coordination was, during the past century, often interpreted as contingent and as a result of the limited material means of pre-industrial societies. Nevertheless, the continued application and gradual adaptation of these urban and architectural patterns throughout periods of industrialization and economic development suggests they respond to both long-lasting housing requirements and piecemeal urban growth. This article surveys the persistence of urban and architectural patterns up to the early twentieth century, showing their resilience in addressing the requirements of modern housing and urbanisation.