For almost a century ornate murals have adorned some of the most important buildings in Mexico.

They were seen as the art of the revolution and a revolution in art. Stories were laid out on the walls in pictoral form so they could be understood and appreciated by people who could not read.

Nowadays people admire them for the artistic value but erosion and the passage of time means that some of them may not be around in another hundred years.

BBC Mundo's Inma Gil reports.