A group of self-styled anarchists moved back into a squat on Kallidromiou Street in the Athens district of Exarchia on Wednesday, just two days after it was evacuated by police.
This is the second time this has occurred at the particular property.
In November, a police operation cleared the building and found Molotov cocktails, suggesting it was a safe house used by anarchists from which to launch attacks on police.
Among the four people arrested at the time was a 43-year-old who was linked in the past to an urban guerrilla group. The building was reoccupied six days after that evacuation operation.