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 (2011), making it the most populous municipality in Norte Region. Gaia along with Porto and 12 other municipalities make up the commonly designated Porto Metropolitan Area.

The North Region or Northern Portugal is the most populous region in Portugal, ahead of Lisbon, and the third most extensive by area. The region has 3,576,205 inhabitants according to the 2017 census, and its area is 21,278 kilometres (13,222 mi) with a density of 173 inhabitants per square kilometre. It is one of five regions of Mainland Portugal. Its main population center is the urban area of Porto, with about one million inhabitants; it includes a larger political metropolitan region with 1.8 million, and an urban-metropolitan agglomeration with 2.99 million inhabitants, including Porto and neighboring cities, such as Braga, Guimarães and Póvoa de Varzim. The Commission of Regional Coordination of the North (CCDR-N) is the agency that coordinates environmental policies, land-use planning, cities and the overall development of this region, supporting local governments and associations.