Located along the Douro river estuary in northern Portugal, Oporto is a registered UNESCO World Heritage Site in 1996. The city's actual name is Porto, but when preceded by a definite article 'O' in Portuguese meaning 'the' in English, it is written as 'o Porto' meaning 'the port' in English. As a result, the English name evolved from oral evolution, is now referred to as 'Oporto' in modern literature. Read More...