Vila Nova de Gaia, or simply Gaia, is a city and a municipality in Porto District in Norte Region, Portugal. It is located south of the city of Porto on the other side of the Douro River. The city proper had a population of 178,255 in 2001. The municipality has an area of 168.46 km². and a total population of 302,295 inhabitants, making it the most populous municipality in Norte Region, and the third most populous in the country, after Lisbon and Sintra.