Thousands of anti-austerity demonstrators gathered in Athens to protest against the visit of German Chancellor Angela Merkel - the woman they blame for much of their financial hardship.
Police scuffled with protesters and fired teargas in response to demonstrators throwing stones and petrol bombs.
Seven thousand police and security officers, including anti-terrorist units and rooftop snipers, were deployed to secure Merkel's safety.
Streets in central Athens were closed and rallies prohibited in the town centre and near streets Merkel had to pass to reach Greek Prime Minister Antonis Samaras's office.
It was the first time since the end of the military junta in 1974 that a ban on street rallies was imposed in Greece.
Three separate protests took place in front of the Greek parliament and workers were called out on a three-hour strike
The economic crisis has rekindled anti-German sentiment that goes back to the Nazi occupation of Greece during the Second World War.
Some demonstrators dressed up as Nazi officers, burned Third Reich flags and chanted slogans such as "No to the Fourth Reich".
Public order minister Nikos Dendias called for calm. "I call on all Greeks and whoever wants to protest to, firstly, safeguard the peace of the city and, above all, the country's image abroad," he said.
But some politicians warned that merkel coulkd expect a rough ride. Alexis Tsipras, leader of the Greek opposition party Syriza, said: "[Merkel] does not come to support Greece, which her policies have brought to the brink. She comes to save the corrupt, disgraced and servile political system. We will give her the welcome she deserves."