ancient, architecture, blue sky, boat, boats, buildings, Cais da Ribeira, church, cityscape, colorful, Douro, Douro river, downtown, embankment, europe, facade, famous place, hill, historic, historical, houses, iron bridge, landmark, multi-colored, old town, oporto, pier, ponte, port wine, porto, portugal, portuguese, rabelo, rabelo boats, ribeira, river, riverside, tourism, tower, town, traditional, transport, travel, travel destination, trip, unesco, urban, view, windows, World Heritage –