Johnny Cash's San Quentin prison concert
22 January 2013 Last updated at 10:27 GMT
US country and western star Johnny Cash campaigned hard to improve conditions for prisoners in the US.
He lobbied the government for prison reform, and performed many concerts inside prisons.
One of the most famous of these was at San Quentin State Prison in California in 1969.
Here is a brief extract from his performance there.
San Quentin (Live), from the album Ring Of Fire: The Legend Of Johnny Cash, Sony Music Entertainment UK Ltd.