Led Zeppelin’s 1971 epic “Stairway to Heaven” is widely regarded by music critics as one of the greatest rock songs of all time. It’s also been one of the most profitable. Clocking in at nearly eight minutes long, the band refused to release the song as a single, which forced fans to shell out more cash to buy the album it appeared on. When coupled with the song’s substantial royalties from radio play, “Stairway to Heaven” has earned at least Continue reading