Made a UNESCO World Heritage Site back in 2001, the majestic Douro is a serene and stunning waterway on the Iberian Peninsula. One of the oldest and most renowned wine regions in the world and fringed by vineyards, many luxury river cruise itineraries here aim to showcase the incredible produce of the Douro. The outlet of the river, and a star feature on any voyage along it, is the picturesque Portuguese city of Porto, renowned for its cobbled streets, impressive bridges and port wine production.