Barcelona (Catalan IPA: [bəɾsəˈlonə], Spanish IPA: [baɾθeˈlona]), is the capital and most populous city of Catalonia and the second largest city in Spain, with a population of 1,605,602 in 2006. It is located on the Mediterranean coast ( [show location on an interactive map] 41°23′N, 2°11′E), between the mouths of the rivers Llobregat and Besòs, and is limited to the west by the Serra de Collserola ridge (512 m/1,680 ft). Barcelona is a major economic centre, with one of Europe's principal Mediterranean ports, and its airport is the second largest in Spain. Founded as a Roman city, Barcelona became the capital of the Counts of Barcelona and 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. 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 county (comarca) of the Barcelonès.