The city has a spotted yet deep history dating back to the 4th century BC. With effects being discovered from several ages and empires, the city has been host to the Visigoths, Romans, Muslim conquerors, and the French. The city is a mixed blend of several cultures which highlights its history. The number of Roman ruins that can be seen in the Museu d'Historia de la Ciutat and the layout of the Barri Gotic, highlight the presence of the Romans somewhere around the early 3rd century. The Cathedral, also known as the Basilica La Seu, is said to have been founded in 343AD, and also highlights that possibility. The city was then conquered by the Visigoths of northern Europe, in the early 5th century and was later invaded by Muslims conquerors in the 8th century.
Spain, since then, saw several changes in power and Barcelona became the capital of an independent state. Eventually, the Castilians came to power and the city developed its own government, the Generalitat. With the discovery of America, Spain's attention got diverted to the Atlantic shores and that heralded decadence in the region's economy.
The 18th century brought renewed demographic and economic growth and by the end of the century, the city had seen an upsurge in the population, nearly tripling and an industrialization that changed the face of the city.
In the 19th century, Barcelona once again became the capital of the Principality. However, the turn of the century brought political unrest and hegemony. Later on, in 1923, the failure of the Mancomunidad Catalana brought a period of dictatorship under Primo de Ribera, which was a serious blow to Catalanism. The Pla Cerda joined the villages around Barcelona with it and changed the city's shape once again.
The civil war marked one of the bloodiest eras of the region and marked the prohibition of all things resembling a Catalan identity. The country suffered considerably under General Franco's dictatorship and missed economic, social, and cultural growth, until the 60's and 70's.
After Franco's death in 1975, Juan Carlos planted the seeds of democracy, which yielded in the first democratic elections in 1977. The nationalist president, who was the last president of the Generalitat before the civil war, Josep Tarradellas, returned to the country and laid down the status of an autonomous community on to Catalonia. Since then, Barcelona and Spain have never ceased development.