There is perhaps no stranger pairing than rock titan Robert Plant and bluegrass diva Alison Krauss. Rolling Stone’s David Fricke caught up with the two in the midst of their sold-out tour for their album Raising Sand, so click below to find out what got Plant into “mountain music” and why Krauss says singing with Plant “is like standing on a cliff.”

• On the Road With Robert Plant and Alison Krauss