Architect Ľudovít (Ludwig) Oelschläger -- Őry Lajos (1896 -- 1984) was probably the most significant personality mainly of the inter-war architecture. However, only little known to the public so far, he worked in the town of Košice during his most productive period in 1924 -- 1945. Here in his hometown and also in Slovakia and Sub-Carpathian Ruthenia, which was the part of the then Czechoslovakia, he left the work of exceptional merit that reaches out to the professional and also to the general public today. He gained respect for the past, classical education and good family background thanks to his rich German Evangelical family in Košice, originating from the Spiš region. Intellectual and spiritual atmosphere of his hometown was close to the one in Budapest, where he gained his university degree, as Košice was part of the Austria -Hungarian monarchy until the end of the First World War. A longer study trip to Germany (1921 - 1922), which took place after his graduation, enabled him to obtain the latest European knowledge in the field. The initial period of Oelschläger's work was closely related to the then Hungarian architecture, which he also perceived through the works of his Budapest colleagues and peers Bogdánfy and Gerlóczy in their architectural studio, where he worked for a certain period (1923). The specific quality of the Oelschläger's architectural works of his early period was also affected by five-year-lasting close cooperation with Hungarian architect G.Z.Boskó (1924 -- 1929). The most impressive result of their cooperation was the Orthodox synagogue and school in Košice (1925, 1926 -- 1927, 1933, NCM), the construction of which was carried out almost in parallel to the Neological synagogue in Košice designed by major Budapest architect L.Kozma. At the end of the 1920's and at the beginning of the 1930's the architect's feeling moved towards simplification. Oelschläger gradually transformed the strong influence of the European modernism in his own way. He abandoned surprisingly easily his own stylish way of abstraction of the historical schema originally combined with the art déco style, and designed his first works, which reflected the current formal, constructional and dispositional preferences of functionalistic architecture. Modernity gradually became a status symbol not only of the higher but also of the middle class, not only in the East of Slovakia but also in the close Sub-Carpathian Ruthenia. At the end of the 1930's, probably under the influence of unfavourable political situation, and also to comply with the requirements of the clients, the architect once again returned to the historicizing concept of architecture in original combination with modernism. In 1945, due to political reasons he involuntarily left Košice with family and spent the rest of his life in Hungary. Only a few original personalities, which "would have gone with the flow" and stood out greatly though, can be found in the architecture of the inter-war period in the territory of Slovakia. The knowledge gained on the basis of many years of research defines the position of architect Oelschläger -- Őry as exceptional in the context of the town of Košice (but also Slovakia, former Sub-Carpathian Ruthenia and Hungary). His works of a large scale as well as the smaller buildings, implemented with remarkable confidence and genuine rendering, formed significantly Košice modernism in 1920's and 1930's. They rank among the most valuable buildings that modernism has bequeathed in architecture in Košice: five structures in Košice, two in Michalovce and one in the High Tatras have been enlisted among the National Cultural Monuments.