Black Sabbath threw together one of the most popular songs in heavy metal history in an afternoon as an afterthought.

Black Sabbath are the undisputed godfathers of heavy metal. Beginning with their eponymous debut and seminal sophomore ... After a succession of influential albums, Sabbath guitarist Tony Iommi ...

Credit: Getty Images/Chris Walter Black Sabbath’s first album is effectively ground zero for heavy metal - and as guitarist Tony Iommi recalled, it was an album made under intense pressure.