BY THE NUMBERS: 'Black Sabbath'

Black Sabbath’s self-titled debut album was released in the U.K. on this day in 1970. To many, it’s considered the birth of heavy metal, and those “many” aren’t wrong.

PLAYLIST: Best Side A/Track 1s

Led Zeppelin’s self-titled debut album was released 49 years ago today (January 12.)  Besides being one of the best albums of all time, Led Zeppelin also has one of the best opening tracks of all time, too.