September 24 - Something Constructive

Hi all, today's trivia.....

After the Spanish Civil War,in 1939,the Catalan language and flag were banned. During the Franco dictatorship one of the few places that Catalan could be spoken freely was within X?What is X?

Hint: As usual something to do with september 24

Ok....The answer is Camp Nou, Barcelona opened on september 24,1957.............