Porto, officially the Ancient, Very Noble, Ever Loyal and Undefeated City of Porto, also known in English as Oporto, is the second largest city in Portugal, after Lisbon. It is the capital of the Porto District and one of the Iberian Peninsula's major urban areas. Porto city proper, which is the entire municipality of Porto, is small compared to its metropolitan area, with an estimated population of 252,687 people in a municipal area of 41.42 km (16 sq mi). As of 2025, Porto's urban area has around 1.4 million people in an area of 2,395 km (925 sq mi), making it the second-largest urban area in Portugal. while the Porto metro area has more than 1.8 million people. It is recognized as a global city with a Gamma + rating from the Globalization and World Cities Research Network.
On the Douro River estuary in northern Portugal, Porto is one of the oldest European centers, and its core was named a World Heritage Site by UNESCO in 1996, as the Historic Centre of Porto, Luiz I Bridge and Monastery of Serra do Pilar. The historic area is also a National Monument of Portugal. The western part of its urban area extends to the coastline of the Atlantic Ocean. Settlement dates back to the 2nd century BC, when it was an outpost of the Roman Republic. Its combined Celtic-Latin name, Portus Cale, has been referred to as the origin of the name Portugal, based on transliteration and oral evolution from Latin.