Barcelona is a city situated on the northeastern coast of Spain, positioned between the mouths of the Llobregat and Besòs rivers and bounded to the west by the Serra de Collserola mountain range. It serves as the capital and largest city of the autonomous community of Catalonia, as well as the second-most populous municipality in Spain after Madrid. The urban area extends into neighboring municipalities within the province of Barcelona, forming a significant metropolitan region that ranks among the largest on the Mediterranean Sea.

According to tradition, the settlement was founded by Phoenicians or Carthaginians who maintained trading posts along the coast, with some attributing its establishment to the general Hamilcar Barca in the third century BC. Under Roman rule, it became Colonia Faventia Julia Augusta Pia Barcino, retaining its political center near the current Plaça de Sant Jaume for over two millennia. During the Middle Ages, it became the capital of the County of Barcelona and later the Crown of Aragon before being overtaken by Valencia. It briefly fell under French control during the Reapers' War and Napoleonic era.

The city features a rich architectural heritage, particularly the works of Antoni Gaudí and Lluís Domènech i Montaner, which are designated UNESCO World Heritage Sites. Its layout includes the medieval Old Town with its Roman grid plan visible in the Gothic Quarter and unique 19th-century street grids. The cathedral, Catedral Basílica Metropolitana de Barcelona, is sometimes called La Seu, while the city is also referred to as Ciutat Comtal or Ciudad Condal due to its history as the seat of the Count of Barcelona.

Barcelona is a major cultural center and tourist destination, renowned for hosting the 1992 Summer Olympics and numerous international sport tournaments. It is home to prestigious institutions like the University of Barcelona and Pompeu Fabra University, alongside the headquarters of the Union for the Mediterranean. The city attracts visitors with its wide variety of attractions, including long sandy beaches, green parks, and a lively nightlife, while locals advise against treating it merely as a beach resort or wearing beachwear in religious sites.

The municipality has a population of 1,731,649 as of 2025, with the broader urban area home to around 5.7 million people. It functions as a major economic and financial hub in southwestern Europe and the main biotech hub in Spain. Transport infrastructure includes the Port of Barcelona, one of Europe's busiest passenger ports, and Barcelona–El Prat Airport, which handles over 50 million passengers annually. The best times to visit are May to June and late August to October for comfortable weather.