The four members of Led Zeppelin certainly didn’t know they were creating an anthem for the ages when they began writing “Stairway to Heaven” in early 1971. But make no mistake: The band was intentional in creating a classic track. Guitarist Jimmy Page once said he aimed to craft a new song with an epic magnitude similar to 1968’s “Dazed and Confused.” “The idea was to have a song which would actually change as we went through it,” Page explained. “Layers would unfold with the instruments as they were coming in, and the drums would be coming in later as the song progressed, and there’d be this…