Viana do Castelo is a municipality and seat of the district of Viana do Castelo in the Norte Region of Portugal. The population in 2011 was 88,725, in an area of 319.02 km2. The urbanized area of the municipality, comprising the city, has a population of approximately 36,148 inhabitants, although the extended densely populated region reaches surrounding municipalities like Caminha and Ponte de Lima with a population above 150,000 inhabitants. It is located on the Portuguese Way path, an alternative path of the Camino de Santiago, and at the mouth of the Lima river.

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.