Ключевые слова: arch, architecture, bank, bridge, bridges, building, city, cityscape, clouds, colorful, concrete, connection, construction, crossing, daytime, douro, europe, evening, green, hill, historic, infrastructure, iron, joao, landmark, maria, metal, old, oporto, ponte, porto, portugal, portuguese, railroad, railway, reflection, river, riverfront, riverside, sao, saunset, skyline, surface, tourism, travel, vertical, walkway, water, waterfront, way,