Thousands of Greeks, including former Prime Minister Alexis Tsipras, marched through central Athens on Sunday evening to mark the anniversary of a violently quashed student uprising in 1973 that helped topple a military junta.
Cypriot students are expected to march on Monday.
The annual march often becomes a focal point for protests against government policies and in recent years against austerity, after a decade-long debt crisis.
Police deployed more than 5,000 officers in central Athens. A helicopter hovered over the central Syntagma Square and neighboring districts through the day.
At the front of the procession, due to end at the U.S. embassy, youths held a blood-stained flag that belonged to the students engaged in the 1973 revolt. Protesters resent Washington for its support of the 1967-1974 military dictatorship.
Tsipras, a leftist who lost parliamentary elections to his conservative rival Kyriakos Mitsotakis in July, took part. Dressed in a leather jacket and jeans Tspiras hooked arms with other officials from the Syriza movement during the procession.
Since Friday, many people have laid wreaths and carnations at the Athens Polytechnic, site of a bloody clampdown on Nov. 17 1973 when tanks smashed through the gates to crush a revolt that heralded the end of the junta.
On Monday, police clashed with students protesting against the shutdown of a prominent Athens university, the University of Economics and Business. Authorities had raided the university to confiscate materials they said were typically used in violent demonstrations.
It was the first time police and protesters had clashed inside university premises since the conservative government’s abolition of academic sanctuary in August.
The sanctuary law, a legacy of the 1973 crackdown on students, left a deep-rooted suspicion towards authority among Greeks.