Barcelona is the capital and most populous city of the Autonomous Community of Catalonia and the second largest city in Spain, with a population of 1,605,602 in 2006. Barcelona is a major economic centre with one of Europe's principal Mediterranean ports, and Barcelona International Airport is the second largest in Spain. 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 hosting the 1992 Summer Olymp. Barcelona has many venues for live music and theatre, including the world-renowned Gran Teatre del Liceu opera theatre, the Teatre Nacional de Catalunya, the Teatre Lliure and the Palau de la Música Catalana concert hall. Barcelona also is home to the Sónar Music Festival which takes place around June every year, and to the Barcelona and Catalonia National Symphonic Orchestra (Orquestra Simfònica de Barcelona i Nacional de Catalunya, usually known as OBC) is the largest symphonic orchestra in Catalon.