It will be interesting to see how everyone reacts. The regional politicians will be under more pressure now to find a solution to the demands of the people who have been asking for more autonomy for years.
The demonstration comes a day after a constitutional court declared that there was no legal basis to recognise Catalonia as a nation.
The ruling also said the Catalan language should not take precedence over Castilian Spanish.
It followed a challenge to the region's statute by the opposition People's Party, which favours Spanish unity.
The statute of autonomy was approved by Catalan voters in a 2006 referendum.
It gave greater powers to the regional parliament in taxation and judicial matters.
