Arguably, some of Metallica's best albums ever were produced by Flemming Rasmussen in Denmark.  Ride the Lightning and Master of Puppets.

Now, for the 30th anniversary of Ride the Lightning, Flemming talks about the recording of the album, and called it "almost effortless".

Apparently, "For Whom the Bell Tolls" was written in the studio.  Watch the video and get more details on the classic metal masterpiece.