Barcelona is the capital, most populous city of the Autonomous Community of Catalonia and the second largest city in Spain, with a population of 1,615,908 in 2008. It is the eleventh-most populous municipality in the European Union and sixth-most populous urban area in the European Union after Paris, London, Ruhr Area, Madrid and Milan with the population 4,185,000. 4,9 million people live in Barcelona metropolitan area. The main part of a union of adjacent cities and municipalities named Área Metropolitana de Barcelona (AMB) with a population of 3,186,461 in area of 636 km² (density 5.010 hab/km²). Barcelona is Europe's largest city on the Mediterranean coast.
It is located on the Mediterranean coast (41°23′N 2°11′E) between the mouths of the rivers Llobregat and Besòs and is bounded to the west by the Serra de Collserola ridge (512 m/1,680 ft).
Barcelona is recognised as a global city because of its importance in finance, commerce, media, entertainment, arts and international trade. Barcelona is a major economic centre with one of Europe's principal Mediterranean ports, and Barcelona International Airport is the second largest in Spain after the Madrid-Barajas Airport (handles about 30 million passengers per year). Founded as a Roman city, Barcelona became the capital of the Counts of Barcelona. After merging with the Kingdom of Aragon, it became one of the most important cities of the Crown of Aragon. Besieged several times during its history, Barcelona is today an important cultural centre and a major tourist destination and has a rich cultural heritage. Particularly renowned are architectural works of Antoni Gaudí and Lluís Domènech i Montaner that have been designated UNESCO World Heritage Sites. The city is well known in recent times for the 1992 Summer Olympics. The headquarters of the Union for the Mediterranean are located in Barcelona.
As the capital of Catalonia, Barcelona houses the seat of the Catalan government, known as the Generalitat de Catalunya; of particular note are the executive branch, the parliament, and the Supreme Court of Catalonia. The city is also the capital of the Barcelonès comarca (shire).
Barcelona is located on the northeast coast of the Iberian Peninsula, facing the Mediterranean Sea, on a plateau approximately 5 km (3 mi) wide limited by the mountain range of Collserola, the Llobregat river to the south-west and the Besòs river to the north. This plateau has 170 km2 (66 sq mi), of which 101 km² (38.9 sq mi) are occupied by the city itself. It is 160 km (100 mi) south of the Pyrenees and the Catalonian border with France.
Collserola, part of the coastal mountain range, shelters the city to the north-west. Its highest point, the peak of Tibidabo, 512 m (1,680 ft) high, offers striking views over the city and is topped by the 288.4 m (946.2 ft) Torre de Collserola, a telecommunications tower that is visible from most of the city. Barcelona is peppered with small hills, most of them urbanized and that gave their name to the neighbourhoods built upon them, such as Carmel (267 m), Putxet (181 m) and Rovira (261 m). The escarpment of Montjuïc (173 m), situated to the southeast, overlooks the harbour and is topped by Montjuïc castle, a fortress built in the 17–18th centuries to control the city as a replacement for the Ciutadella. Today, the fortress is a museum and Montjuïc is home to several sporting and cultural venues, as well as Barcelona's biggest park and gardens.
The city borders are the municipalities of Santa Coloma de Gramenet and Sant Adrià de Besòs to the north; L'Hospitalet de Llobregat and Esplugues de Llobregat to the south; the Mediterranean Sea to the east; and Montcada i Reixac and Sant Cugat del Vallès to the west.
Barcelona has a Mediterranean climate, with mild, humid winters and warm, dry summers. Barcelona is located on the eastern coast of the Iberian Peninsula, so Atlantic west winds often arrive in Barcelona with low humidity, producing no rain. The proximity of the Atlantic, its latitude, and the relief, are the reasons why the summers are not as dry as in most other Mediterranean Basin locations. Lows (not surface lows but high-atmospheric "cold invasions") can easily affect the area of Barcelona (and Catalonia), causing storms, particularly in August. Some years, the beginning of June is still cool and rainy, like April and May. Together with August, September, October and November these months are the wettest of the year. The driest are February, March, June and July. As in many parts of Catalonia, the annual weather pattern varies greatly from year to year.
So, on average, the rainy seasons are spring and autumn, and the dry ones are winter and summer. The order from wettest to driest is: AUT-SPR-WIN-SUM. The Western Mediterranean Climate is one of the most irregular climates in the world. For instance, one year October can be very dry and July or February wet months. Barcelona and London have the same annual rainfall, but London's climate is not as irregular and torrential as Barcelona's.
As for temperatures, December, January and February are the coldest months, averaging temperatures of 9°C at the Airport and over 10°C in the city. July and August are the hottest months, averaging temperatures of 24°C . The highest temperature recorded in the city centre is 38.6°C. The coldest temperature recorded was –6.7 °C on 11 February 1956 and –5°C on 12 January 1985. However, in the 19th century –9.6°C was recorded in January 1896.
At the Fabra Observatory, situated on the Tibidabo hill, 412 m above the sea level, the record summer temperature is 39.8°C on 7 July 1982, and the lowest temperature ever registered, -10.0°C on 11 February 1956. Near the hills and the Airport annual rainfall reaches 650 mm, and in the city centre about 600 mm.