"A Poem on the Underground Wall" is a song written by Paul Simon, first released as a recording on the Simon and Garfunkel album Parsley, Sage, Rosemary and Thyme. The Simon and Garfunkel boxed set Old Friends includes a live version of the song, prefaced by an anecdote from Garfunkel about its origin: he explains that a photo shoot for the cover of the album Wednesday Morning, 3 A.M. was ruined because the subway wall they had intended to use as a backdrop had obscenities written on it.

A rerelease of Parsley, Sage, Rosemary and Thyme includes a demo version of the song, performed only by Simon, that includes a false start before the completed third take.