Muslims gather in a place in Piraeus every year around early October for the Ashura. The date is not fixed, so make sure to check each year's date.
The event starts at 13:00 in the afternoon and ends around 17:00 to 18:00. They are gathered to mourn for the death of Husayn ibn Ali. The mourning goes to the extreme when they start hurting themselves, using a pair of chains with five blades attached on one side, causing injuries to their backs. This is not done by everyone and is not obligatory, but some people want to inflict the pain and suffering of Husayn.
Most of the people are crying, mourning and hitting their chests in a certain rhythm, extending their arms, hitting and changing arms. This is repeated many times.