Tens of thousands of people from all over the country converged on Spain's capital to hold a large anti-austerity demonstration today.
By mid-morning several major roads had been blocked as buses unloaded protesters at 10 rendezvous points from which marches began.
The main organiser, Social Summit, an association of more than 150 organisations, and the Workers' Commissions and General Workers trade unions, said the demonstration was called to protest against government cuts during the country's financial crisis.
The Interior Ministry's regional office said it expects more than half a million people to reach Christopher Columbus Square in the centre of Madrid, where union leaders would make speeches.
Some marchers unfurled banners with slogans such as "Let's go! They are ruining the country and we have to stop them."
"This government's policies are causing too much hurt," said Ignacio Fernandez Toxo, the secretary general of the Workers' Commissions. "It's a lie that there isn't another way to restore the economy."
Large anti-austerity protests also were planned in neighbouring Portugal.
The Madrid protest comes four days after another anti-government gathering in the north-eastern city of Barcelona which police said included some 1.5 million demonstrators.
"We've had our pay cut. We don't get the firefighting training and equipment we need. There are more students and fewer teachers in our children's classrooms, and healthcare is also being cut," said fireman Carlos Melgaves who was marching in a group of about 50 firefighters. "We can't take it anymore."
Speaking in Nicosia, Cyprus, where Europe's finance ministers were meeting today, Spain's economy minister, Luis de Guindos, said his government is aware it is asking sacrifices of Spanish society. "These sacrifices are absolutely unavoidable if we are to correct the difficult economic climate we are experiencing," he said. "We are laying the foundations for a recovery."
Spain, the fourth largest economy of the 17 countries that use the euro as a single currency, is stuck in a double-dip recession and unemployment is close to 25%.
Spanish Prime Minister Mariano Rajoy has accepted a loan of up to 100 billion euros to rescue banks reeling from a collapse of the country's real estate and construction industries. His government also has faced punishingly high interest rates while raising money on bond markets to keep the economy in liquidity.
The country is widely expected to ask to sell its bonds to the European Central Bank, but the conditions attached have been the subject of ongoing negotiations.
Mr Rajoy's government has introduced stinging cuts and tax increases in a bid to reduce the deficit and to reassure investors and the euro zone's financial officials.
In Portugal, another package of recently announced government austerity measures could turn the nation's sullen acceptance of belt-tightening into an explosion of anger similar to that seen in Greece over the past two years.
Last week Portuguese Prime Minister Pedro Passos Coelho announced an increase in workers' social security contributions to 18% of their monthly salary from 11%. The cut is equivalent to a net monthly wage.
Portuguese Finance Minister Vitor Gaspar said income taxes will go up next year and public employees will lose either their Christmas or vacation bonus, roughly equivalent to a month's income. Many pensioners will lose both.