Antonin Dvorák's Symphony No. 9 in E Minor, Op. 95, B. 178 'From the New World': II. Largo
Louis Armstrong's 'West End Blues'
This song is fairly representative of early New Orleans style jazz, in which almost all the musicians were soloing at the same time. It's also a 12 bar blues.
The rhythmless sequence in the beginning that Louis plays is also iconic.
Rock and pop:
Bob Dylan's "Visions of Johanna"
Many consider this song to be Dylan's (the Nobel prize winner in literature, this year) most lyrically expressive and dense song.
The youtube link below is a live performance.