Bilbao is a city in northern Spain, the largest city in the province of Biscay and in the Basque Country as a whole. Bilbao is the tenth largest city in Spain, with a population of 345,141 as of 2015. The Bilbao metropolitan area has roughly 1 million inhabitants, making it one of the most populous metropolitan areas in northern Spain; with a population of 875,552 the comarca of Greater Bilbao is the fifth-largest urban area in Spain. Bilbao is also the main urban area in what is defined as the Greater Basque region. Bilbao is situated in the north-central part of Spain, some south of the Bay of Biscay, where the economic social development is located, where the estuary of Bilbao is formed. Its main urban core is surrounded by two small mountain ranges with an average elevation of . After its foundation in the early 14th century by Diego López V de Haro, head of the powerful Haro family, Bilbao was a commercial hub of the Basque Country that enjoyed significant importance in Green Spain. This was due to its port activity based on the export of iron extracted from the Biscayan quarries. Throughout the nineteenth century and the beginning of the twentieth, Bilbao experienced heavy industrialisation, making it the centre of the second-most industrialised region of Spain, behind Barcelona. and continued by infrastructure investments, such as the airport terminal, the rapid transit system, the tram line, the Alhóndiga, and the currently under development Abandoibarra and Zorrozaurre renewal projects. Bilbao is also home to football club Athletic Club de Bilbao, a significant symbol for Basque nationalism due to its promotion of Basque players and one of the most successful clubs in Spanish football history.