Supporters of Catalonia's independence from Spain have joined hands to form a 400km (250-mile) human chain across the region in support of their cause.
Hundreds of thousands of people took part in the event, which comes on Catalonia's national day.
Regional President Artur Mas has been urging Madrid to allow the region a referendum on independence in 2014.
But he has been unable to get the central government's approval for such a vote in the north-eastern region.
Catalonia - one of Spain's most developed regions - already has a wide degree of autonomy, but the economic crisis has fuelled Catalan nationalism.
Pro-independence feelings go back centuries, and the Spanish Civil War in the 1930s strengthened animosity between Madrid and Barcelona.
Lines of protesters, many wearing the red-and-yellow Catalan flag, stretched from the French border, through the city of Barcelona and south along the coast towards the regional border with Valencia.
Carme Forcadell, president of the Catalan National Assembly which organised the human chain, called the event "historic".
"The Catalan people have reaffirmed their determination to be a free state,'' he said.
The BBC's Tom Burridge in Barcelona said the human chain was another strong show of popular support in Catalonia for the idea of a vote on independence.
Speaking to reporters before the action, Mr Mas said the drive for independence was entering a "decisive phase".
He later told the BBC that if Madrid continues to block a referendum he will turn regional elections - due in 2016 - into a vote on independence.
"My intent is to try to negotiate with the central government a legal framework in order to organise, to hold a referendum, next year in Catalonia," he said.
"This is our intention. We don't know if the Spanish government will accept this kind of deal."
However, Spain's deputy prime minister, Soraya Saenz de Santamaria, said Mr Mas was promoting political divisions.
"The worst thing a politician can do is force people to separate,'' she said.
A recent poll for Spain's Cadena Ser radio station has found that support in Catalonia for the vote has risen slightly to 81%, our correspondent reports.
He adds that 52% of those questioned said they would vote in favour independence from Spain.
However, public opinion in Spain remains strongly opposed to the idea, and according to the Spanish constitution, a referendum in Catalonia would be "unconstitutional".