Oswald Haerdtl's Espresso Arabia am Kohlmarkt in context of the Viennese Coffee House Culture Design innovations in the 1950s within the Modern Age The Espresso Arabia am Kohlmarkt, designed by Oswald Haerdtl in 1950, is an early example of the rising Espresso Culture in Vienna. Also, it is the origin of the Espresso style that was developed by Haerdtl for this variant of Viennese coffee houses. Haerdtl's design became a significant role model for the subsequent generation of Espressos; beyond that, it has an impact on the presentation of related business models like the Viennese Café-Konditorei (a cross between coffee bar and confectionary) or modern cafés. Regardless of its significance, the Arabia am Kohlmarkt was demolished in 1999, thus a major contemporary of the development of design in the 1950s was lost. To date, we still lack a well-grounded architectural and art-historical evaluation of the Arabia am Kohlmarkt; the present treatise is aimed at filling this gap. The Espresso Arabia am Kohlmarkt ist subjected to a detailed analysis. For this purpose, the archived heritage of Oswald Haerdtl was consulted, and a comparative study of complementary literature performed. The well-grounded description of the Arabia am Kohlmarkt focuses on the objective examination and chronological classification of the existing archive data, which partially led to deviations from the prevalent opinions. Therefore, it was possible to draw conclusions about the original interior design and the design intentions of the architect. Furthermore, the genesis of the project exemplifies how the Espresso has been established in Vienna in the 1950s as a Viennese interpretation of the Italian Caffé-Bars. The new business model "Espresso" and its design were developed from the specific situation of the 1950s, which was characterized by the technical improvements and promising future prospects. In the 1950s and 1960s, the Viennese Espresso culture peaks out prominently, but the new business model `Espresso- is overwhelmed by the Viennes Coffee House Tradition and its design replaced by new design trends shortly after. The Viennese reception of the Espresso concept was significantly influenced by the centuries-old tradition of the Viennese Coffee House Culture. Hence, its customs and its idealized architectonical form in Historism will be introduced in an incipient chapter. Nevertheless, the classical Viennese coffee house design already starts changing during the Viennese Modern Age since 1900 and was adapted to new circumstances. The contrarian design trends of this period, with special attention to Oswald Haerdtl`s mentors Josef Hoffman and Josef Frank, are highlighted in the course of this work. Both of them crucially influenced Haerdtl`s stylistic development and hence his Espresso style.