There are a few classic songs, in my opinion, that should never be covered -- no matter who you are. Classics are classics for a reason, please don't butcher them.

However, this particular Led Zeppelin cover is so fantastic that it made Robert Plant cry... and if you're a Zeppelin fan, I would challenge you not to cry as well.

It happened back on December 2, at the Kennedy Center Honors. Nancy and Ann Wilson of Heart performed 'Stairway to Heaven' in front of the three remaining members of the legendary British rock band.