Barcelona is the capital city of the autonomous community of Catalonia in Spain and Spain's second most populated city, with a population of 1.6 million within its administrative limits. Its urban area extends beyond the administrative city limits with a population of around 4.7 million people, being the sixth-most populous urban area in the European Union after Paris, London, Madrid, the Ruhr area, and Milan. It is the largest metropolis on the Mediterranean Sea, located on the coast between the mouths of the rivers Llobregat and Besòs, and bounded to the west by the Serra de Collserola mountain range, the tallest peak of which is 512 metres (1,680 ft) high.
Founded as a Roman city, in the Middle Ages Barcelona became the capital of the County of Barcelona. After merging with the Kingdom of Aragon, Barcelona continued to be an important city in the Crown of Aragon as an economical and administrative center of this Crown and the capital of the Principality of Catalonia. Besieged several times during its history, Barcelona has a rich cultural heritage and is today an important cultural center and a major tourist destination. Particularly renowned are the architectural works of Antoni Gaudí and Lluís Domènech i Montaner, which have been designated UNESCO World Heritage Sites. The headquarters of the Union for the Mediterranean is located in Barcelona. The city is known for hosting the 1992 Summer Olympics as well as world-class conferences and expositions and also many international sport tournaments.
Barcelona is one of the world's leading tourist, economic, trade fair and cultural centers, and its influence in commerce, education, entertainment, media, fashion, science, and the arts all contribute to its status as one of the world's major global cities. It is a major cultural and economic center in southwestern Europe, 24th in the world (before Zürich, after Frankfurt) and a financial center. In 2008 it was the fourth most economically powerful city by GDP in the European Union and 35th in the world with GDP amounting to €177 billion. In 2012 Barcelona had a GDP of $170 billion; it is leading Spain in both employment rate and GDP per capita change.
In 2009 the city was ranked Europe's third and one of the world's most successful as a city brand. In the same year the city was ranked Europe's fourth best city for business and fastest improving European city, with growth improved by 17% per year, but it has since been in a full recession with declines in both employment and GDP per capita, with some recent signs of the beginning of an economic recovery. Since 2011 Barcelona is a leading smart city in Europe. Barcelona is a transport hub with the Port of Barcelona being one of Europe's principal seaports and busiest European passenger port, an international airport, Barcelona–El Prat Airport, which handles above 35 million passengers per year, an extensive motorway network and a high-speed rail line with a link to France and the rest of Europe.
The Barri Gòtic (Catalan for "Gothic Quarter") is the center of the old city of Barcelona. Many of the buildings date from medieval times, some from as far back as the Roman settlement of Barcelona. Catalan modernista architecture (related to the movement known as Art Nouveau in the rest of Europe), developed between 1885 and 1950 and left an important legacy in Barcelona. Several of these buildings are World Heritage Sites. Especially remarkable is the work of architect Antoni Gaudí, which can be seen throughout the city. His best-known work is the immense but still unfinished church of the Sagrada Família, which has been under construction since 1882, and is still financed by private donations. As of 2007, completion is planned for 2026.
Barcelona was also home to Mies van der Rohe's Barcelona Pavilion. Designed in 1929 for the International Exposition for Germany, it is an iconic building that came to symbolize modern architecture as the embodiment of van der Rohe's aphorisms "less is more" and "God is in the details." The Barcelona pavilion was intended as a temporary structure, and was torn down in 1930 less than a year after it was constructed. A modern re-creation by Spanish architects now stands in Barcelona, however, constructed in 1986.
Barcelona won the 1999 RIBA Royal Gold Medal for its architecture, the first (and as of 2015, only) time that the winner has been a city, and not an individual architect.
Barcelona beach was listed as number one in a list of the top ten city beaches in the world according to National Geographic and Discovery Channel. Barcelona contains seven beaches, totalling 4.5 kilometres (3 miles) (2.8 mi) of coastline. Sant Sebastià, Barceloneta and Somorrostro beaches, both 1,100 m (3,610 ft) in length, are the largest, oldest and the most-frequented beaches in Barcelona.
The Olympic Harbour separates them from the other city beaches: Nova Icària, Bogatell, Mar Bella, Nova Mar Bella and Llevant. These beaches (ranging from 400 to 640 m (1,310 to 2,100 ft) were opened as a result of the city restructuring to host the 1992 Summer Olympics, when a great number of industrial buildings were demolished. At present, the beach sand is artificially replenished given that storms regularly remove large quantities of material. The 2004 Universal Forum of Cultures left the city a large concrete bathing zone on the eastmost part of the city's coastline.