Piano sonatas (Beethoven)
Ludwig van Beethoven wrote his 32 piano sonatas between 1795 and 1822. Although originally not intended to be a meaningful whole, as a set they compose one of the most important collections of works in the history of music. Hans von Bülow called them "The New Testament" of the piano literature (Johann Sebastian Bach's "The Well-Tempered Clavier" being "The Old Testament").
Polonaise, Op. 89 (Beethoven)
The Polonaise in C major, Op. 89, by Ludwig van Beethoven is a polonaise for solo piano, published in 1815. He composed it in December 1814, at a time when the polonaise was becoming a popular dance and class marker among the European nobility. Beethoven was presented as a prominent artist at the ongoing Congress of Vienna, where he met the visiting Russian Empress Elizabeth Alexeievna. He dedicated the polonaise to the Empress, and was compensated with a sum of 50 ducats. The piece is Beethoven's first and only published standalone polonaise, and is notable as a precursor to Chopin's more well-known polonaises.