Beethoven#s four-movement Sonata in A-flat major Op.26 belongs to his most popular works. It is dedicated to Prince Lichnowsky, one of his most generous patrons and the dedicatee of, for example, the Grande Sonate pathétique Op.13 and Symphony No.2 Op.35. The work#s initial drafts date from 1800#01; it was first published in March 1802. This demanding sonata is highly varied in its form: it begins with a set of variations and contains the famous Marcia funebre sulla morte d#un Eroe as its third movement, earning it the nickname #Sonata with the Funeral March#. The identity of the title#s eroe (hero) remains unknown to the present day. The march was performed at Beethoven#s funeral on 29 March 1827 in an arrangement for orchestra. For this Bärenreiter edition Jonathan Del Mar, possibly as one of the first editors of a modern edition, consulted the composer#s autograph in the original. This enabled him to decipher details of Beethoven#s handwriting in particular with regard to the exact notation of doubtful slurs. The result is a most reliable and thoroughly-researched musical text. Differing readings and editorial decisions are documented in the Critical Commentary. The edition has been finely engraved and includes practical page turns. Information on central issues of historical performance practice (pedalling, ornaments, tempo, dynamics, articulation) is provided in a detailed chapter.