This is a short itinerary, perfect for a few days' excursion out of Porto into the beautiful and intensively cultivated Douro Valley, where the grapes for vinho verde (green wine) are grown. Because the climate does not allow time for the grapes to ripen fully, the wine produced is quite light with a slight sparkle. The Douro is a swift river, dropping over 120 meters during its 160-kilometer journey across Portugal, and carving deep, precipitous canyons into the landscape. The unwieldy geography has not daunted the people who live on the steep but fertile slopes along its banks, however, and the sight of tiny white villages clinging to the hillsides, surrounded by narrow strips of fields stepping down to the river, ranks among the most picturesque in the country.