Huge video screens erected in Barcelona's streets broadcast archive footage of the Berlin Wall coming down, and of Nelson Mandela toppling South African apartheid - meant to draw associations to Catalans' own struggle for freedom - as Spain's northeast region holds a much-disputed vote on whether to secede and form a new country in Europe.

The Catalan capital Barcelona was transformed into a massive pro-independence rally, with fiery speeches, concerts of traditional Catalan folk songs and whole families draped in Catalan flags. A wide central thoroughfare was closed to traffic, where video monitors showed footage of Berlin 25 years go, juxtaposed with images from Catalonia's own history.

Long fight for autonomy

"I'd rather be a first-class Catalan, than a third-class Spaniard!" says Marc-Ignasi Corral-Baqués, a 49-year-old Catalan doctor who joined the crowds. "The Spanish government doesn't treat us equally. It doesn't respect our culture. Bullfights and flamenco are not my culture -- that's Spain, not us."

Catalans are going to the polls Sunday to answer two questions: "Do you want Catalonia to be a state? If so, do you want that state to be independent?"

With their own language and culture, Catalans have long sought autonomy from the Spanish central government in Madrid. But this marks the first time they're voting explicitly on the issue, as well as on whether to break away and found an entirely new country. The two-pronged ballot could be used to negotiate a new fiscal pact with Madrid, if not independence.

Difficulties to get voters to the polls

Turnout is critical, if the poll is to truly reflect Catalans' wishes for the future. But that's tricky when Madrid has declared the whole process illegal. Even Catalan leaders acknowledge the voting is non-binding, informal and unofficial. They call it a "participatory process," not a referendum. No political change is mandatory afterward.

"What clinched the Scots' situation is that you had over 85% participation [in Scotland's independence referendum in September]," says Enric Ucelay-Da Cal, a historian at Pompeu Fabra University in Barcelona. "So how are you going to get the people who are not mobilized to vote, when it's non-binding anyway? This is like, 'I have better things to do.'"

For three days leading up to Sunday's poll, volunteers manned a phone bank in downtown Barcelona, going through the phone book and dialing up residents, encouraging them to vote and explaining where they could do so. "The most important thing is that people get the necessary information to decide," says Maria Medina Roca, a volunteer who phoned hundreds of homes. "And also it's important to participate, because it's the only way of letting us know what they feel like, what they want and where we want to go as a society."

The Catalan regional government recruited volunteers like Maria to administer Sunday's vote, after Spain's high court ordered preparations for the vote halted. Volunteers have replaced civil servants, who risked violating Spanish law if they were to staff polling stations themselves. More than 1,300 voting spots are set up across Catalonia, but many are in different schools and government buildings than in regular elections.

While Spain's government has repeatedly declared the Catalan vote illegal, Prime Minister Mariano Rajoy appeared to have little recourse to prevent it, short of using force -- which might look bad, in a modern European democracy.

"We would love to have pictures of the Spanish police marching in here to withdraw the ballot boxes," says Miquel Strubell, a retired university professor and Catalan activist. "But I think Rajoy is shrewd enough to realize that would be disastrous."

A region divided

Opinion polls show a large majority of Catalans have been in favor of holding this independence vote, despite opposition from Madrid. But they show that Catalan society is roughly divided, 50-50, on whether to break away from Spain.

In a Barcelona office building tucked away from the boisterous pro-independence street rallies, a group of Catalans read out a manifesto against independence, before a handful of TV cameras. "This isn't a referendum, nor a consultation, nor even the culmination of a so-called 'participatory process,'" said Joaquim Coll, vice president of Societat Civil Catalana, a Catalan group opposed to Sunday's vote. He spoke in Catalan. "It's a mere act of propaganda… and we discourage Catalans from participation or any kind of collaboration in this act."

Coll accuses the Catalan regional government of using public buildings and taxpayers' money for a partisan cause that does not reflect the wishes of all Catalans. It's unclear how many residents of Catalonia share Coll's point of view. "Sometimes it seems like in Catalonia, there are only people who want independence. But it's not like this!" says Susana Beltran, another member of the same group, who says she's felt social pressure to join the pro-independence movement. "The problem is that people who don't want this are afraid to speak out. They don't want problems with their friends, with their jobs, in life in general."

Catalonia has long had its own strong, distinct cultural identity, reinforced through nearly four decades of repression under the Spanish military dictator Francisco Franco, who died in 1975. Under his rule, the Catalan language and holidays were banned.

But only a small minority of Catalans supported the idea of independence until three years ago, when there was a groundswell of pro-independence feeling amid Spain's economic crisis. Many Catalans believe their wealthy region has been unfairly subsidizing poorer parts of Spain. For many, it is an economic arrangement - not their cultural identity nor history - that fuels separatist sentiment.