"The End" by the Doors.
This song is probably the most haunting, but beautiful song I have ever heard. I was real late discovering the Doors and their music, but now I am completely obsessed with it. I remember hearing "The End" in it's entirety for the first time when I visited the Rock and Roll Hall of Fame in Cleveland. I was in this Beatles exhibit (bored) and suddenly I heard this song coming from upstairs. I followed the music into the Doors exhibit and was just entranced.