Porto (Portuguese pronunciation: [ËˆpoÉ¾tu]), also known as Oporto (English), is the second largest city in Portugal. Its administrative limits (an area of 41.66 kmÂ²/16 sq.mi) includes a population of 220,000 inhabitants distributed within 15 civil parishes. The urbanized area of Porto, which extends beyond the administrative limits of the city, has a population of 1.1 million in an area of 389 km2 (150 sq mi), making it the second-largest urban area in Portugal. The Porto Metropolitan Area includes approximately 1.3 million people, and is recognized as a Gamma-level global city by the Globalization and World Cities (GaWC) Study Group. 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. Its settlement dates back several centuries, when it was an outpost of the Roman Empire. Its Latin name, Portus Cale, has been referred to as the origin for the name "Portugal," based on transliteration and oral evolution from Latin. In Portuguese the city is spelled with a definite article as "o Porto" (English: the port). Consequently, its English name evolved from a misinterpretation of the oral pronunciation and referred to as "Oporto" in modern literature and by many speakers. One of Portugal's internationally famous exports, port wine, is named for Porto, since the metropolitan area, and in particular the adegas of Vila Nova de Gaia, were responsible for the production and export of the fortified wine.