1. Canon in D by Pachelbel
2. Fur Elise by Beethoven
3. Ode to Joy by Beethoven
4. Scarborough Fair traditional English.
5. Jesu, Joy of Man's Desiring by Bach
6. Classical Gas by Mason Williams
7. Moonlight Sonata by Beethoven
8. Ave Maria by Bach
9. Sonata in C Major, K. 545 by Mozart
10. Suite Miniature (Six Pieces for One Piano, Four Hands) by Cesar Cui
11. La Donna é Mobile Verdihref
12. Clair de Lune by Debussy
13. Habanera by Bizet
14. Moonlight Sonata by Beethoven
15. Adagio from Sonatina No. 6 by Mozart
16. Hungarian Dance No. 5 by Brahms
17. Sarabande in F Major by Handel
18. Wedding March by Mendelssohn
19. Nocturne by Chopin
20. Gloria in Excelsis by Vivaldi
Find direct links to download free classical sheet music with MIDI previews for all of the above classical songs and more at Free Classical Sheet Music

Nice list but Fur Elise & Moonlight Sonata should be first

The actual list of top classical sheet music is taken from a very recent record of digital classical sheet music being downloaded online be musicians and others at Download Sheet Music. The top 20 classical music is changing all the time, and the list is only a snapshot at the time I made the post.
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Ah ! Ah! nice stuff, I really agree with the classment (fond of Pachelbel's canon)
Is there any way to suggest a new classical sheet music of mines? it's the 'Rondo Veniziano -Heandel, Bach' i'm just listening to it more and more, never sick of it!

I'm gonna have to say.... (in no particular order)

Schumann's symphony no 2
Rimsky-Korsakov's Scheherezade
Mussorgsky's Pictures at an Exhibition
Wagner's the Flying Dutchman
Beethoven's Symphony No. 5
Stravinsky's the firebird suite
Tchaikovsky's Symphony no 6
Tchaikovsky's swan lake
Gershwin's An American in Paris
Elgar's Enigma Variations
Mozart's various serenades

these are some of the best pieces, imo