200 years ago, in late autumn 1817, Beethoven began to write his first sketches of the most monumental of his piano sonatas, the Sonata Op. 106 nicknamed 'Hammerklavier'. In autumn 2017, Wiener Urtext Edition presents a newly revised separate edition of this exceptional work. The incomplete source material has been reassessed and explained in both preface and critical report. In addition, the edition contains an interpretative essay by Johann Sonnleitner which sheds a new light on Beethoven's problematic metronome markings.