The Chilean muralists who defied Pinochet
6 September 2013 Last updated at 01:21 BST
Founded in 1968 by a group of young Chilean communists, the Brigada Ramona Parra (BRP) took its name from Ramona Parra, a 19-year-old woman shot dead by the police during a protest in Santiago in 1946.
Inspired by the revolutionary spirit of the late 1960s, the members of the BRP headed out onto Santiago's streets to paint.
They saw murals not only as a way of brightening up the city's drab walls, but of fomenting radical social change.
In 1970, BRP propaganda helped propel the Socialist candidate Salvador Allende into the presidential palace.
But in 1973, their work was cut short. Gen Augusto Pinochet seized power in a military coup and the Communist Party was outlawed.
BRP activists were tortured and driven into exile. The military government painted over their murals.
The BRP went underground but continued to paint in defiance of the dictatorship.
With the return to democracy in 1990, the BRP came out of hiding.
To this day, the collective paints murals in Chile, championing contemporary causes such as workers' and indigenous rights and the campaign for education reform.
As Chileans mark the 40th anniversary of the Pinochet coup, BBC News heard from members of the BRP as they worked on a new mural.
Video journalist: Gideon Long