Through different case studies, this course unit analyses the contribution of archaeological methods to the knowledge of Portuguese heritage, from Prehistory to Middle Ages. It introduces the criteria used, over time, to carry out research on the archaeological heritage, and to its protection, promotion and dissemination. Archaeology of cities and historical centers (Urban Archaeology) is another subject area to be addressed, due to its importance in the redevelopment of city life - a concern of many municipalities. The importance of the archaeological heritage in regional land-use and development plans is another issue to be addressed. Some paradigmatic case studies will be analised in detail, and thereby, their importance demonstrated, either at economical or social or cultural levels.