The Douro Valley's terraced schist hillsides, carved by hand along the river, are some of the steepest and hardest-farmed vineyards in the world — and among the oldest demarcated wine regions, dating to 1756. It's best known as the home of Port, the fortified wine made by stopping fermentation partway through with grape spirit, leaving natural sweetness behind. But a growing number of producers now make serious dry reds and whites from the same field blends of indigenous grapes, labelled simply as Douro DOC.

Key grapes: Touriga Nacional, Touriga Franca, Tinta Roriz, Tinta Barroca