The importance that Franz Schuberts music has on any classical musician is almost indisputable. His output stretches over all the important genres of his time and while he never wrote solo pieces specifically for the viola, one work has gained an essential status in the viola repertoire. That work being the sonata for arpeggione and piano, D. 821. Volumes have been written on Schubert, his style, early 19th century Vienna, romanticism, classicism and the formal development of the sonata form as well as the rise of the bourgeoise music scene. Perhaps less is written on the viola and especially the arpeggione. My aim in this paper is to answer the question,” why arpeggione?”. Why does this work hold such a high status in our repertoire? I shall approach this question by both presenting the sonata in question by drawing its background and generally the style and background of Schubert and early romantic Vienna, and also by introducing two alternative early romantic sonatas, both by esteemed composers and written originally for viola. Lastly, I shall dissect the mostly arrangement-related challenges of the arpeggione sonata and discuss different reasons for it having attained such an important role in spite of its problematic suitability for the viola.