Activists from 20 countries have gathered in Athens to demonstrate against rising attacks by a neo-Nazi movement critics call the most dangerous in Europe.
The protest is backed by scores of civil rights groups, anti-racist movements and imposing intellectuals, including Nobel laureates Dario Fo and Bernard Kouchner.
It comes amid heightened shows of vigilantism and attacks on migrants by Golden Dawn, the once-tiny far-right group that catapulted onto Greece's tumultuous political scene last June after winning 18 seats in the country's 300-member parliament.
Organisers planning a silent yet symbolic march from the nation's sprawling legislature to the Acropolis - one emblem of democracy to another - say the demonstration will trigger a wake-up call not only for Greece but for other European nations facing rises in far-right extremism.
"In Greece, like elsewhere in Europe, racism, anti-Semitism and neo-Nazism are growing without any strong and determined mobilisations from the democrats," said Benjamin Abtan, the chief organiser and president of the European Grassroot Antiracist Movement (EGAM).
"The whole of European society must get involved.
"All individuals have the responsibility to make neo-Nazis understand that their success story in Greece will not whet the appetite of other far-right extremists in Europe."
With 80% of Asian and African migrants entering Europe through Greece, the country has seen a dramatic influx of undocumented refugees in the past decade.
That upsurge has drastically changed the make-up of what used to be a fairly homogeneous but traditionally xenophobic society.
Rising rates of crime, which have spiked in the wake of the Greek financial crisis, have led many disillusioned Greeks to side with extremist parties like Golden Dawn.
The party campaigned on an anti-immigration platform in the June elections, proposing the planting of mines along Greece's northeast borders to prevent the entry of illegal immigrants.
At least four of its elected lawmakers face criminal investigations for allegedly aiding and abetting anti-immigrant attacks - something the party vehemently denies.
Controversy over Golden Dawn has spawned domestic and international resistance.
Last month, Facebook stripped the party's page from its site for inciting racial violence.
However, a recent opinion poll showed the group's support base has nearly doubled from the 7% of votes it picked up in June, overtaking the socialist PASOK party.
"We're here to stay," said Ilias Kasidiaris, a spokesman for Golden Dawn. "We'll consolidate our support as other parties crumble.
"Let them have their march. Let them say whatever they want.
"We know we are in the hearts of the people. We are a party of Greeks for the Greeks."