Around 25,000 people marched through Athens on Sunday in closely watched demonstrations to mark the 51st anniversary of the pro-democracy uprising that helped topple military rule in Greece, police said.
The protests are held every year to commemorate the 1973 Athens Polytechnic protests that killed 24 people, when the ruling junta sent troops to break up an anti-government uprising.
As the commemoration is often marred by far-left violence on the sidelines, more than 5,500 officers were deployed on Sunday.
They were backed by riot squads, drones and helicopters monitoring key locations, including the US and Israeli embassies, police said earlier.
More than 110 people were detained during checks made before the march, according to police sources.
Much of the city centre was closed off to traffic and central Athens metro stations closed early.
The brutal crackdown on the 1973 student-led, anti-junta demonstrations shocked Europe and is generally considered to have broken the dictatorship's grip on power, leading to the restoration of democracy months later.
Sunday's march began at the Polytechnic campus headquarters and was fronted by students carrying a bloodstained Greek flag that flew over the Polytechnic's iron gate the night it crushed by a tank. Many protesters also carried Palestinian flags.
Various civil society groups, anti-authoritarian collectives, opposition parties, workers' unions headed toward the US Embassy to protest against Washington's support for the Greek military dictatorship during the Cold War, and then to the Israeli Embassy.
Student associations chanted "The Polytechnic uprising lives on, calling us to fight" and "Freedom in Palestine".
Prime Minister Kyriakos Mitsotakis on Sunday emphasised the importance of free parliamentary democracy.
"The message of resistance emanating from the Polytechnic uprising is an enduring symbol of progress which is neither trapped in the past nor sacrificed to party exploitation," he posted on social media.
"That is why, 51 years later, it still shines. To signal loyalty to democracy. Faith in unity. And the prospect of a better life."
Protests were held nationwide, including in the cities of Thessaloniki, Patras in the Peloponnese and Heraklion in Crete.
In Thessaloniki, where 8,000 people protested,a group of young people hurled Molotov cocktails at riot police after the march ended. Officers responded with tear gas and flash bombs.
