More than 5,000 police officers have been deployed across central Athens as the city implements sweeping security measures for the 52nd anniversary of the 1973 Polytechnic Uprising.
The operation, one of the largest in recent years, includes widespread road closures and the shutdown of major metro stations.
Thousands of officers from riot police, state security, and anti-terrorism units were stationed around the Athens Polytechnic, the U.S. and Israeli embassies, and the Exarchia district.
Plainclothes officers were also conducting preventive checks.
Authorities are monitoring the area from the air using drones and a helicopter, with rooftops in Exarchia under special observation.
Armored water cannon vehicles were positioned on standby in case of unrest.
Public transport face severe disruptions.
Police have ordered key central metro stations, including Syntagma, Evangelismos, and Omonia, to close at 2 p.m. Monday. Trains will pass through without stopping until further notice.
Bus and trolley routes are being rerouted, and extensive parking bans and road closures are in effect until 6 a.m. Tuesday.
The annual march from the Polytechnic to the U.S. Embassy remains a politically charged event, drawing student groups, unions, and left-wing parties.
The demonstration often concludes with clashes between police and small groups of youths in Exarchia. Authorities said the tight security is aimed at ensuring public safety.