'''Piano Sonata No. 21''' in C major, Op. 53, known as the '''''Waldstein''''', is one of the three most notable sonatas of his middle period (the other two being the ''Appassionata'', Op. 57, and ''Les Adieux'', Op. 81a). Completed in summer 1804 and surpassing Beethoven's previous piano sonatas in its scope, the "Waldstein" is a key early work of Beethoven's 'Heroic' decade (1803-1812) and set a standard for piano composition in the grand manner.
The sonata's name derives from Beethoven's dedication to his close friend and patron Count Ferdinand Ernst Gabriel von Waldstein of Vienna. Like the ''Archduke'' Trio (one of many pieces dedicated to Archduke Rudolph), it is named for Waldstein even though other works are dedicated to him. It is also known as 'L'Aurora' (The Dawn) in Italian, for the sonority of the opening chords of the third movement, thought to conjure an image of daybreak.
It is one of Beethoven's greatest and most technically challenging piano sonatas. The first section of the Rondo requires a simultaneous pedal trill, high melody and rapid left hand runs while its coda's glissando octaves, written in dialogue between the hands, compel even advanced performers to play in a simplified version since it is more demanding to play on the heavier action of a modern piano than on an early 19th Century instrument.