Thousands of Milan residents, led by Mayor Giuliano Pisapia, have marched through Italy's financial capital to protest violence that left much of downtown trashed on May Day.

Hundreds of the marchers on Sunday also removed graffiti and helped repair other damage wreaked by protesters who rampaged through downtown two days earlier while VIPs were inaugurating the world's fair the city is hosting, Expo 2015, which opened on its outskirts.

The vandals smashed bank and shop windows, torched parked cars and damaged traffic lights, breaking off from a peaceful Labor Day march on Friday that protested a high-speed rail line being built in northern Italy and other big construction projects.

Expo runs through October.