Hard to beat Beethoven, but among the songs of my lifetime, I'd have to say that "Amelia" by Joni Mitchell is great for the pictures she paints in your mind with the lyrics.
In the various YouTubes of Joni performing this song, it's never quite the same, but all good...
Joni Mitchell- Amelia live 1983
Amelia (cut from Joni Mitchell's Shadows & Light DVD if I'm not mistaken).
Amelia, audio track from Joni Mitchell's Hejira album.