SAN FRANCISCO (KOVR/CNN NEWSOURCE/WKRC) - A unique recording has been unearthed in California.

The recording is from April 24, 1968 when Johnny Cash performed at the Carousel Ballroom in San Francisco.

Hundreds of fans crowded inside the venue to hear Cash that night.

While no photos of the event exist, the whole thing is recorded on audio tape.

The performance included the help of legendary audio engineer Owsley Stanley.