The main march took place in Locri in Calabria - the toe of Italy's boot, but sister marches were organized across the country alongside other events aimed at raising awareness of mafia violence.
Father Luigi Ciotti, the founder of anti-mafia organization Libera, led the march together with Pietro Grasso, the president of the Italian Senate and a prominent anti-mafia magistrate.
Families of mafia victims took place in the protest, as well as demonstrators of all ages and backgrounds. Among them was a group of migrant minors who had arrived to Calabria by boat in recent months.
Protesters carry banners with the slogan 'The mafia kills... so does silence.'
In total, at least 10,000 people were expected to participate in the Locri event - see the livestream below.
March 21st 2017 is the first officially recognized Day of Remembrance for the Victims of Mafia Violence, though Libera has been marking the date with demonstrations and other events since 1996. This year, the day has the slogan: "Places of hope, testimonies of beauty."
Simultaneous marches are taking place in cities across the country, and the day is also being marked by events in schools and cultural organizations.
Video showing marchers in the northern region of Liguria.
Libera's president, Daniela Marcone, described the official recognition of the day as "an important step" in the continuing fight against mafia extortion and violence.
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Antimafia police during a Naples raid on clan members. Photo: Roberto Salamone/AFP