The song's riff has a surprising origin. Slash told MusicRadar.com
: "It is definitely a metal riff but it was actually inspired by some music I heard when I was in Spain at a hotel. It was the kind of music you'd never have guessed could inspire it in a million years. I got the melody stuff in my head and your brain has a way of turning things around. When I got to the gig that night in the dressing room I turned it into this other thing and that's what Halo is."