Led Zeppelin are currently facing a complicated court case as a trustee of Spirit frontman Randy California sues them for copyright infringment on their song 'Stairway To Heaven'. But that's just got us thinking about that classic album it was taken from.

Led ZeppelinLed Zeppelin IV is our Album Of The Day

The artist... Led Zeppelin formed in London in 1968 with Jimmy Page, Robert Plant, John Paul Jones and John Bonham. They are generally thought of as one of the very first heavy metal outfits, but they took much influence from blues, folk and psychedelia. They've sold between 200 and 300 million records around the world and were inducted into the Rock and Roll Hall of Fame in 1995.

More: The Led Zeppelin copyright trial begins

The album... Their first four album titles might be lacking in creativity, but the same can't be said for their content - particularly when it came to the Diamond certified untitled release commonly referred to as 'Led Zeppelin IV'. Released in 1971 on Atlantic Records, this was the album that propelled them to stadiums and featured their most famous song 'Stairway To Heaven'. It was an all round success both commercially and critically, ending the critic bashing they received for 'Led Zeppelin III'.

Why you need to hear it... This was Led Zeppelin at their songwriting peak. While they released seminal track after seminal track throughout their career, 'Led Zeppelin IV' saw eight of the greatest songs they'd ever produced and cemented them of one of the most important musical pioneers in rock history.

The best song... 'Black Dog'. 'Stairway To Heaven' might be their signature tune but the first track from the album sealed the record as one of their best. Named after a rather randy Labrador Retriever that roamed the studios, it was inspired by Muddy Waters and was an attempt by Page to subvert that groove into something you could even boogie to.

Where are they now? Currently in court over allegations that they copied the riff from Spirit's song 'Taurus' for their smash hit 'Stairway To Heaven'. In terms of music, the last thing they released was a live album in 2012 entitled 'Celebration Day'; a concert recorded at London's O2 Arena in 2007.