The Douro river starts its epic journey deep in the mountains of northern Spain before winding its way westwards through the towns of Valladolid and Zamora and some stunning scenery.
For a while, the river then forms a natural frontier between Spain and Portugal. Look out in particular for the whitewashed houses and the port vineyards perched on riverside slopes.
Towns along this stretch of river towards the coast include pretty Pinhao, Regua and Bitetos, and after 557 miles the river finally empties into the Atlantic at the great city of Porto. Portugals second city is best known for its output of the famous fortified wine and it is well worth visiting one of the lodges and museums for a tasting. Taylors Port Lodge is just across the river in Vila Nova de Gaia.