Lawmakers backed drastic cuts in wages, pensions and jobs on Sunday as the price of a 130 billion euro ($170 billion) bailout by the European Union and International Monetary Fund to avert a messy default that would send shockwaves through the euro zone.
The cuts include a 22 percent reduction in the minimum wage and 150,000 jobs from the public sector workforce by 2015.
Scenes of running battles between police and rioters and flames engulfing cinemas, shops and banks underscored a sense of deepening turmoil in the country after more than four years of recession and two of punishing austerity.
The riots spread to Greece's second city of Thessaloniki, towns across the country and the islands of Crete and Corfu. In all, 150 shops were looted in the capital and 93 buildings set ablaze, wrecked or seriously damaged.
Occupy United claimed that 15 of the burned buildings were banks.
About 100 people - including 68 police - were wounded and 130 detained.
Athens city authorities said some of the wrecked buildings were of particular cultural, historic and architectural value.
The Attikon cinema, housed in a neo-classical building dating from 1870, was left a blackened shell.
The rioters were a minority, say various reports, yet others claim they numbered over 100,000 and spoke to the groundswell of anger among Greeks who say their living standards are already collapsing and more austerity will only deepen their misery.
Unemployment in Greece reached 20.9 percent in November, and half of young Greeks are jobless.
Meanwhile, on Twitter, photographs began circulating that identify several members of Greek parliament who were relaxing and watching a football game allegedly as the city of Athens burned.