Prelude, Op. 28, No. 20 (Chopin)

The Prelude Op. 28, No. 20, in C minor by Frédéric Chopin has been dubbed the "Funeral March" by Hans von Bülow but is commonly known as the "Chord Prelude" due to its slow progression of quarter note chords.
The prelude was originally written in two sections of four measures, ending at m. 9. Chopin later added a repeat of the last four measures at a softer level, with an expressive swell before the final cadence.
Bar 3 ambiguity.
In many printed scores (for example "Chopin Masterpieces for Solo Piano", Dover Publications Ltd 1998), the last E of bar 3 in the right hand has no flat accidental to cancel the natural accidental of the previous E in the same bar. Therefore, this second E should also be played as E. However, in most performances you will hear an E, in contradiction to the printed score. Arthur Rubinstein's mono recording of the entire set of Op. 28 on RCA, and "Could It Be Magic" by Barry Manilow are some of the few recordings where the E is played as natural.
It is rumoured that Polish scores show the flat accidental and that all others versions are incorrect due to a type-setting error.
On page 64 of "Chopin, An Introduction to His Piano Works" (2005), Willard A. Palmer notes that "[a]ccording to the editors of the Oxford edition, Chopin is supposed to have added a flat sign before the E in a copy belonging to one of his pupils. It does not appear in the Autograph or the original editions." 
Musicologist Jean-Jacques Eigeldinger posits that Chopin intended to include the flat accidental, citing both manuscripts with the accidental (Jane Stirling's, George Sand's, Cheremetieff's) and Auguste Franchomme's transcriptions of the prelude for other instruments, all of which include the flat or its transposed equivalent.
Cultural legacy.
There are a number of references to this prelude in contemporary culture, and these are just a few examples.