and driest of the subregions, and stretches all the way to the Spanish border. It has of vineyards and is the source of many wines of very good quality. As it is the least accessible of the three subregions, it is the most recently planted, and it is still expanding. Terraced vineyards are very common in the Douro region. Vineyards dedicated to Port production are usually planted on schist while areas with granite-based soils are used for table wine production. Grapes The principal grape varieties of the Douro region include the black grapes Bastardo, Mourisco tinto, Tinta Amarela, Tinta Barroca, Tinta Cão, Tinta Roriz (the same as Spain's Tempranillo), Touriga Francesa and Touriga Nacional, and the white grapes Donzelinho branco, Gouveio, Malvasia Fina, Rabigato, and Viosinho. A large number of grape varieties are grown in the Douro region, most of them local Portuguese grapes. For a long time, the grape varieties grown in the Douro were not very well studied. Vineyards of mixed plantation were the norm, and most of the time, the vineyard owners didn't know which grape varieties they were growing. A pioneering effort were made in the 1970s which identified Touriga Nacional, Tinta Roriz, Touriga Franca, Tinta Cão and Tinta Barroca as the prime dark-skinned grape varieties. Tinta Amarela and the teinturier Sousão has later come to be included among the varieties that attract the most interest. This work was important for creating the new wave of top Douro wines and has also led to a greater focus on the grape varieties that go into Port wine. Most top quintas now replant with single-variety vineyards and focus on a limited number of varieties, but older, mixed vineyards will remain in production for many decades to come. Gallery See also List of Portuguese wine regions Duriense VR, a lower-level Vinho Regional designation for wine from the same area as Douro DOC Quinta classification of Port vineyards in the Douro Factory House References External links Companhia Turística do Douro Cruises in the Douro River on traditional "Rabelo" DouroValley.eu - Main tourism website The Wine Anorak: Spotlight on Portugal's Douro region O Douro: Touristic Portugal's Douro region World Heritage Sites in Portugal Wine regions of Portugal Portuguese products with protected designation of origin Port wine National monuments in Vila Real District de:Alto Douro nl:Alto Douro ja:アルト・ドウロ・ワイン生産地域 pl:Alto Douro pt:Região Vinhateira do Alto Douro ro:Douro DOC fi:Alto Douro