Around one million people have filled central Barcelona to celebrate Catalonia's commemorative day and boost a bid for independence which has left deep divisions almost a year after it brought Spain to a constitutional crisis.
Tractors bearing red-and-yellow Catalan flags rolled into Barcelona from rural areas and separatists in red T-shirts bearing the slogan "Let's build the Republic!" chanted and sang.
Tuesday's huge turnout, estimated by local police, was a response to a call from Catalan regional president Quim Torra and his predecessor Carles Puigdemont, who fled to Brussels last October after Madrid dismissed his government, to show continued support for independence from Spain.
Socialist Prime Minister Pedro Sanchez, who took office in June, has taken a more conciliatory approach than his conservative predecessor Mariano Rajoy but has stood firm against a vote on or move towards independence.
Watching Tuesday's protest on the broad avenue that slices diagonally through Barcelona, 59-year-old psychologist Montse Martin said the movement needed to regain momentum.
"Let's see if from today there will be a turning point and we will be able to move forward," she said. "We have to get down to work and not focus so much on what has happened, as serious as it was, but look to the future."
The September 11 "Diada" celebration marks the fall of Barcelona to Spain in 1714, and has been adopted by independence activists in recent years.
It falls just over a year after Puigdemont's administration held a referendum which Madrid sent riot police to try to stop, and made a unilateral declaration of independence.
Rajoy then imposed direct rule, on the basis of Spain's constitution, which states the country is indivisible.
Torra and other attendees at the march wore yellow ribbons representing nine politicians and activists awaiting trial in jail for their role in the independence bid.
Their trials are expected to start later this year, a potential new source of tension. Sanchez told a Senate session on Tuesday that what Catalonia needed was "law and dialogue".
Australian Associated Press