The angry mob shouted "hands off the youth" and "no fascists in the schools" as they walked the streets. In one of the most shocking rallies the country has seen in recent years, downtown Athens has a huge fireball and several flames. In one picture you can see the armed police with shields crushing through the fire, sending tear gas to the crowd.
The violence used to erupt as a group of masked youths broke away from the march and threw stones at the police.
More than 2,000 police officers were deployed in the area and had to use tear gas to disperse the crowd.
The authorities formed guard bands in front of Parliament and in the hotels of the city, while a helicopter hovered over the central Syntagma Square.
Two demonstrators were temporarily arrested and one of them was injured during the brief riots, a police officer confirmed.
It is assumed that a second rally is planned later in the evening.
On the night of December 6, 2008, hours after Grigoropoulos was shot, thousands of people hit the streets of Athens, burning cars and looting shop windows.
The riots, which were fueled by anger over unemployment and economic hardship in the wake of Greece's debt crisis, lasted for weeks.
Police officer Epaminondas Korkoneas, 38, was sentenced to life imprisonment in 2010 for murdering Mr Grigoropoulos.
The verdict of a jury of judges and jurors was 4-3 for the sentencing of Mr. Korkoneas for deliberately shooting Mr. Grigoropoulos.
Vassilios Saraliotis, 32, patrol partner of Mr. Korkoneas, was sentenced to 10 years imprisonment for complicity.
Due to the turmoil, the process was relocated from Athens to Amfissa – a small town 120 miles west of the capital.