Located in North-eastern Portugal, within the River Douro basin, surrounded by craggy mountains that give it very particular soil and climacteric characteristics, this region spreads over a total area of approximately 250 000 hectares and is divided into three sub-regions that differ greatly from each other not only as regards the weather but also for socio-economic reasons.
The existing characteristics in the Douro region affect the economic use that is made of the natural resources and the activities developed there.
Formally, viticulture was only greatly widespread in the upper stretches of the Douro River, which is why many authors adopted the expression 'Upper Douro' when they referred to the winemaking region known today as the Lower and Upper Corgo.
One of the original boundaries that separated the so-called 'Alto Douro' from the 'Douro Superior' (very upper Douro) was the Cachão de Valeira canyon. This geological obstacle consisted of a huge granite outcrop that prevented navigation beyond this obstacle. The differences between the two areas were truly visible, be it only the spreading vineyards below it.
Later, with the removal of the block of granite during the reign of queen Dona Maria II, viticulture spread eastwards, albeit less extensively so, in the truly Upper Douro.
Following the administrative reforms of 1936, the area below the canyon was subdivided into two sub-regions, the Lower Corgo and the Upper Corgo, and these designations were also applied to the different wines produced in both these sub-regions. The Lower Corgo has the largest amount of land under vine. It extends from Barqueiros on the North bank of the Douro and Barrô on the South bank, to the point where the River Corgo and the Ribeiro de Temilobos flow into the Douro at Régua.
The Upper Corgo extends upstream from that point to the Cachão de Valeira and is less covered with vineyards. The Upper Douro, the name now exclusively applied to the area above the Cachão de Valeira, extends east up to the Spanish border.