Bilbao (Basque: Bilbo) is a city in northern Spain, the largest city in the province of Biscay and in the Basque Country as a whole. It is also the largest city proper in northern Spain. Bilbao is the tenth largest city in Spain, with a population of about 350,000. 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 near 900,000 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 16 kilometres (10 mi) 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 400 metres (1,300 ft). Its climate is shaped by the Bay of Biscay low-pressure systems and mild air, moderating summer temperatures by Iberian standards, with low sunshine and high rainfall. The annual temperature range is low for its latitude. The Bilbao metropolitan area comprises about 47% of the total population of the Basque autonomous community, out of which a 15% is registered in the municipality of Bilbao.

Bilbao is a relevant transport hub for northern Spain. Bilbao is connected to three major motorways and a series of minor roads of national and provincial level. The city lies on two international roads, the European route E70 that follows the coast of the Bay of Biscay and the cities of Santander and Gijón to the west and with Eibar, San Sebastián and Bordeaux to the east. The European route E80 connects the city with inner Spain to the south, including Burgos and Salamanca and continuing to Lisbon, and Toulouse to the north. The AP-68 motorway (European road E-804) starts in the city, joining with Vitoria-Gasteiz, Logroño and ending in Zaragoza. Bilbao is served by the Bilbao Airport (IATA: BIO, ICAO: LEBB), the busiest terminal in the Basque Country and in the entire Northern coast, with more than 5.4 million passengers in 2018. It is located 12 km (7.46 mi) north of the borough, between the municipalities of Loiu and Sondika.