Following the examples of Tuscany and Burgundy, many European wine regions are attempting to launch themselves as tourist destinations. Now it is the turn of Portugal’s Douro Valley, which runs for 100 miles from Porto to the Spanish border. Best known for making Port, one of the world’s greatest fortified wines, the Douro Valley also produces a variety of excellent table wines. The other surprise in the Douro is the extraordinary beauty of its landscape, which the Portuguese writer Miguel Torga once described as a “geological poem.” The river winds between steep hills planted with vineyards and dotted with handsome quintas (wine estates) and villages framed by cypress trees.