Behind them were big contingents of hospital workers, council workers and the Metro workers who had stopped all the trains in the region with their morning walkout.
The public sector union federation Adedy had called the strike against a new third austerity agreement imposed by the European Union (EU).
Among other attacks, it could mean overturning the decision to rehire the cleaners and other workers who were sacked by the previous government.
The rally sent a clear message that this is only the beginning of the resistance.
The strike—and the people getting out on the street to protest—had an effect in parliament.
There’s a lot of anger among the rank and file of prime minister Alexis Tsipras’ left wing party Syriza.
They mobilised for a vote against an austerity package in Greece’s recent referendum, only for the government to do a U-turn and agree to an even worse one.
So Syriza trade unionists, local committees and internal bodies have been coming out against the decision.
This led to a much bigger rebellion inside parliament when it voted on the first round of measures in the deal.
The rebellion went beyond the ranks of the party’s Left Platform. Some 32 Syriza MPs, including four ministers, voted no.
Tsipras had made every effort to calm this rebellion.
Before the vote he gave an interview telling would-be rebels that voting no would mean lining up with German finance minister Wolfgang Schauble, who would rather see Greece kicked out of the euro.
Tsipras praised the two highest profile rebels, speaker of parliament Zoi Konstantopoulou and former finance minister Yannis Varoufakis, and talked down the threat of expulsions.
He argued that it was worth voting yes to defend a left wing government that could soften the impact of the cuts.
But at the same time he undermined this by sending police to disperse the protesters outside parliament.
When Syriza came into office they removed the barriers erected by the previous government to keep protesters away from parliament. Last night they replaced those barriers with teargas.
Adedy is considering another strike next week as MPs vote on the second wave of measures. Other unions—such as the dockers and electricity workers facing privatisation—could walk out after that.
A cabinet reshuffle is imminent, and there is open speculation from the highest levels of the government that elections could be called within months.
The Socialist Workers Party (SEK) is holding a rally in Athens this evening to mark 50 years since the uprising of July 1965.
July 2015 looks set to bring a strike wave, an election campaign—or both.