The series of lectures introduces students to the historiography of the 20th century architecture, explaining the basic theoretical and methodological issues. The lectures start with the basic modernist architectural concepts from the 18th to the 19th centuries, without which one cannot understand the period in question. It takes into account the political-economic and cultural character of the 19th century, which is defined by industrialization, rapid urbanization and the general transformation of social organization and its needs. An important development trend is also the constitution of the original architectural styles legitimizing the autonomy of the emerging nation states. The transformation of the ideological climate, along with the economic and technological development after World War One, influenced the transformation of demands concerning the form and function of architecture, urban design and regional planning. The course is focused on introducing the avant-garde movements in their specific cultural, national and copyright modifications. Typical world trends are compared with the Czech local development, while taking their specifications into consideration. The lecture is also focused on centralization and etatization manifestations of totalitarian regimes in the war and the postwar periods. Special attention is also paid to the application of the socialist-realist canon in the Czech architecture practiced by the former leaders of the avant-garde from the period between the World Wars. The lectures also deal with the institutional history of the field.