[Resumo proveniente da fonte]

The interest that the study of borders has to understand the medieval settlement of the upper valley of the Coa river led us to make this approach to the evolution of the Portuguese borderline in the territory since the 12th century to the 17th century, marked by several episodes of advances and retreats. The fortifications that were the bastions of territorial claim and that contributed to these cross-border dynamics in the region will be highlighted, marked by some conflicts and constant redefinitions of the municipal terms. All these historical and archaeological collected data were placed in digital cartographic base, sometimes extended to the territory between the rivers Douro and Tejo, where were represented some spatial analyses using the computer tools available in geographic information systems (GIS), to produce density and visibility phenomena and three-dimensional terrain models.