Norte or Northern Portugal is the most populous region in Portugal, ahead of Lisbon, and the third most extensive by area. The region has 3,689,173 inhabitants according to the 2011 census, and its area is 21,278 km² (density of 173 inhabitants per square kilometre). It is one of five regions of Mainland Portugal (NUTS II subdivisions). 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 a number of urban areas in Northwestern Portugal, ranging from Braga to Aveiro. 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.Northern Portugal is a culturally varied region. It is a land of dense vegetation and profound historic and cultural wealth. What is now Northern Portugal was first settled by various pre-Celtic and Celtic tribes before being explored by a number of Mediterranean civilizations, including Greek settlements in its river-mouths, trade with the Carthaginians, conquest by the Romans, invasion by Germanic peoples, and attacks by the Moors and the Vikings.