Last week was the 40th anniversary of one of the greatest albums in Rock n' Roll history, Led Zeppelin IV. The fact that that album sounds as good today as it did then is really saying something. Led Zeppelin, and certainly that album in particular, garners new fans everyday. It's pretty cool to see kids discovering Zeppelin for the first time, and it's also cool to know "our" music stands the test of time. While the anniversary was a week ago, I saw this and thought it was just to cool not to share. So, kick back, turn up your speakers, and revel in the ultimate "Stairway" mashup below.