Pro-independence supporters took to Barcelona's streets in their thousands to protest the ongoing trial of Catalan leaders.
A dozen separatist leaders — nine of whom have been jailed since 2017 — are in the dock for their role in a referendum and declaration of independence from Madrid.
Spanish courts deem both illegal and the country's public prosecutor is seeking prison terms of up to 25 years.
Up to 200,000 people — according to figures from local police — turned out for the march on Saturday evening.
"I came here today because there are people, with kids, that have been jailed for a long time. It's unfair because we all voted, so we should all be in jail," Josefina Soler, a 70-year-old retiree, told Reuters.
"It is a shame to see how they judge in Madrid our legitimate representatives with all the impunity of the world," said Santi Margalef, a 61-year-old farmer.
The protest comes in the week that Spain's Prime Minister Pedro Sánchez called a general election for April 28.
That was necessary because Catalan pro-independence parties helped defeat the government's 2019 budget bill.
Sánchez has said he is against a vote on self-determination in Catalonia but his dialogue with the leaders of the north-east region has angered conservatives.
There were demonstrations in Madrid last weekend after Sánchez said he would appoint a rapporteur for talks with Catalan separatists.
But the Popular Party and Ciudadanos said such a move would be giving in to separatist pressure and called for an early general election.
The biggest absence from the separatists' trial on Tuesday was former Catalonia president Carles Puigdemont.
Puigdemont, who fled Spain in October 2017, held a press conference in Berlin as the proceedings in Madrid were getting underway.
Asked why he wasn't at home facing justice, he replied: "I want to return to my home, I want to return to my family. But I want to return to a real democracy with a clear separation of powers and that is not possible in Spain."