Valongo (Portuguese pronunciation: [vɐˈlõɡu] ) is a Portuguese municipality located in the District of Porto, the city population is 18,698, and the municipality is composed of 5 parishes, of which three are cities (Alfena, Valongo and Ermesinde) and has a total population of 97,814 inhabitants.The two most populous cities (and parishes) in the Valongo municipality are Ermesinde, with a population of 38,315, which is essentially a residential suburb of Oporto (Porto) and Alfena which has the most industry in the municipality.