Barcelona, second largest city in Spain and the country’s principal industrial center. Barcelona is the capital of Catalonia, Spain's autonomous northeast region, located 150 km south of the French border. Its location on the Mediterranean Sea, hemmed in by the deltas of the Besós and the Llobregat rivers and the Collserola Mountains, accounts for its temperate, humid climate. The mountains, which rise to more than 518 m (1,700 ft.) within 13 km (8 mi) of the city center, form a dramatic backdrop.