Here is some information about Barcelona and the province of Catalunya, where Barcelona is located. The city dates back to 300 B.C.E. when the Romans founded a small city here. It grew over the years and at one time during the Middle Ages (the 13th Century), the city was the capital of Aragon and Catalunya, the most powerful city-states in the Mediterranean Sea.
http://www.bcn.es/english/laciutat/barcelona/ The website from the City of Barcelona, with all kinds of interesting information about the city.
http://www.en.mhcat.net/ The website of the Museum of the History of Catalunya with virtual tours of the region's history.
Because Barcelona is in Spain, spanish is of course spoken, but the citizens here have another official language called catalan, which everyone who is born learns to speak. Catalan is very different from spanish, and in many ways is similar to french.