QUOTE(Sam-ChopinFan @ Mar 21 2010, 05:49 PM)

I think one of the hardest has to be a couple of the Liszt Hungarian Rhapsodies (No.2 in Particular). But of course there's the Chopin Etudes, Rach Concerto's etc
This thread runs on and on, and people keep coming up with the same handful of pieces as most difficult - which they are most definitely not - not by a country mile. Anyone that thinks they are has simply not heard or studied enough of the piano repertoire.
Liszt wrote a lot of very difficult to play pieces (B minor sonata, Apres une lecture de Dante etc.) but Hungarian Rhapsody No 2 is not amongst them. In the grand scheme of things it is really not a very difficult piece at all. It just looks it from the way that some pianists exaggerate its physical demands. And Liszt's most difficult pieces are probably not the most diffficult of all.
The difficulty of the Chopin Etudes is not merely playing them - with stubborn hard work they are do-able by any diploma-level pianist - it is playing them well which is difficult - removing those last little rough edges - which explains why some great pianists (e.g. Friedrich Gulda) neither recorded them nor played them in public.
However, the Rachmaninov concertos really are difficult. Number two is hard enough, but number three is moving into the realms of impossible for mere mortals.
But none of these difficult works is remotely close to being the "most difficult" piano piece.
For most pianists Gaspard de la Nuit is tougher than any of them but I can't agree with Wobby that it is the most difficult of all. Nor can I agree with Invidia that Le Gibet is its most difficult part. It might be hard to make convincing music from its sparse texture, but most of us could at least make something of it, whereas our Ondine would limp along at 3/4 speed (if that) and we probably could not even hit most of the notes of Scarbo - at least not in the right order, or at the right time.
There are literally hundreds of pieces that make HR2 seem like a beginner's exercise. Just for starters, a better contender fro most difficult piece would be Alkan's Concerto for Solo Piano (I am not suggesting that it IS the most diffficult - but it is in a different league of difficulty to any of the old chestnuts mentioned above).
The scariest score must surely be Sorabji's Opus Clavicembalisticum. Whether it is the most difficult is a question for very much better pianists than me to decide because for me, above a certain not-very-high level, it all becomes impossible.