With its source 2 060m up in Spain, the River Douro is an impetuous and unpredictable watercourse. It roars through the Spanish Meseta before flowing into the Atlantic above Porto. On the way, it has down the ages cut a steep granite valley (famed for its vineyards) through the mountainous north of Portugal, which can be discovered on the Porto vineyards or lower Douro routes through the Vihno Verde region, a landscape dotted with quintas (wineries), solares (manors) and churches.