Riot police have fired tear gas at half a million protesters trying to reach the presidential compound in the Algerian capital.
The "march for democracy" was sparked by nearly two months of bloody unrest. At least 150 people were injured in violent confrontations and French TV reported four deaths.
The Algiers march was called by Berber groups but supported by numerous opposition parties. The demonstrators were demanding justice and more freedom from the military-backed government after weeks of deadly riots.
Demonstrators, some carrying knives and hatchets, destroyed the facades of buildings with stones and iron bars. They also smashed the glass front of the Sofitel, the most luxurious hotel in Algiers, and destroyed dozens of cars.
Sporadic rioting continued along the main arteries of Algiers hours after the march ended and streets were strewn with broken lampposts.
There was no official estimate of the number of marchers but informal estimates reached about half a million.
The Berbers, who claim to be the original inhabitants of North Africa, have had tense relations with Algiers for decades as they press their demand for official recognition of the Berber language, Tamazight.
The march comes after at least 52 people were killed during 40 days of rioting in the mountainous Berber region.