The Best Piano Works of the 20th Century

My nonimations are:

Vignt Regards sur L’Enfant Jesus by Olivier Messiaen, and

The People United Will Never be Defeated by Frederic Rzewski

How about you?
I'm partial to early 20th century 'modern' piano-e.g., Scriabin.
Spare, angular, but not atonal. 
 But the one of the best artists who 'covered' him was his son-in-law and the recordings--from Russia- are not great. 
Should we add particular interpretation we like? There are some recordings of a certain work that give an overall better impression. I am not talking about "audiophile" standards, but about the music itself. of course, it will depend on a personal taste, but it may be worth a try.

Having said that, all my favorites are from way before 20th century, save for Satie, so I cannot even participate. I will peruse this thread to explore, though. Thanks everybody.
As far as "improvised" 20th century music is concerned, two of the most fertile minds and virtuoso pianists were Art Tatum ( "I got rhythm" 1940 from the "California melodies" radio program) and Bud Powell ( "Tempus Fugit" 1949 Clef records)  I love Scriabin and Nancarrow,but when it comes to emotionally charged,thrilling,fly by the seat of your pants piano I bow down to these two recordings. And yeah,Jazz WAS the greatest music of the 20th century....Was, I emphasize.
If you're interested in something relatively current,and noted as "Gourmet Jazz",  I will highly recommend Bill Laurance : " After Sun,"" Swift", or "Flint "( "Ready Wednesday" - My personal fav ).  I originally downloaded Flint from HD Tracks, then "Live at Union Chapel" and "After Sun" recently, but "Swift" was from his website.  All are exceptionally well recorded and addictive.

Happy listening...