The Portuguese wine-growing region is named after the 900 km long river, on whose very steep slopes with extreme inclination the vineyards are situated. The river has its source in the Spanish province of Soria(Castilla y León), flows through northern Spain as the "Duero" and then through northern Portugal as the "Douro" until it finally flows into the Atlantic Ocean at the city of Porto. The river forms the Portuguese-Spanish border for more than 100 kilometres, after which the port wine region extends into Portugal for the same length of time. The Douro has cut a deep valley into the slate granite mountains on whose slopes the port wine grows. As early as 1756, under the Prime Minister Marquês de Pombal (1699-1782), in order to protect the authenticity of the port wine, Douro was first defined within its borders as one of the oldest protected wine regions in the world and later classified as a DOC area. However, the "Vinho do Porto" or "Porto" is not named after its region of origin Douro, but after the port city from which it is shipped. For more than two centuries, this applied exclusively to port wine. It was not until 1979 that this was extended to include unpritified wines. The success of the famous red wine "Barca Velha" from the Ferreira winery, but later also of the "Redomo" from Niepoort and the "Grande Escolha" from Quinta do Côtto contributed to this success.