Description Porto, occasionally also known as Oporto in English is the second-largest city in Portugal, after Lisbon, as well as one of the major urban areas in Southern Europe and the capital of the second major great urban area in Portugal. It is recognized as a Gamma-level global city by the Globalization and World Cities (GaWC) Study Group, being one of five cities on the Iberian Peninsula with global city status, the others being Madrid, Barcelona, Lisbon and Valencia.Located along the Douro river estuary in northern Portugal, Porto is one of the oldest European centres, and registered as a World Heritage Site by UNESCO in 1996.