This article deals with permanence and change in the traditional architecture of southern Portugal, adopting the town and landscape of Mértola as a case study. This research conveys how the relationship between the vernacular architecture, the territory and the site is not immune to the course of history, reflecting a profound change in the ways of living over time. In methodological terms, the research focuses on surveying and characterizing architectural diversity in both the
rural context (with the definition of various landscape subunits) and the urban context (delimiting the various urban subunits). This concludes that the architectural specificity, in both contexts, is subordinate to the same processes of historical change which nevertheless acquire a circumstantial dimension. These processes
include the readable influences of models and ways of living arriving from abroad and contemplate: the transition of the courtyard house from the Islamic medieval period to the compact house of the Christian medieval and modern periods; the consolidation, diversification and ennobling of different housing types during the Ancien Régime; and the profound transformations of domestic architecture following the advent of Liberalism.