The author recalls the role and significance of Chair of Polish Architecture established in 1922 by Prof. Dr. Oskar Sosnowski in the Department of Architecture at Warsaw Politechnic. Its target was the interdisciplinary activity of architects, historians of art and ethnographers. Work was conducted in the following sections: folk art and rural construction, the history of art, inventory measurements, town planning, painting, and history of fortifications, as well as in studios dealing with interiors and equipment, liturgical (sacral) art, Jewish art and garden architecture. The amassed collections of measurements, photographs and slides totalled thousands, and the number of publications exceeded twenty. During the second world war the activity of the Chair was interrupted only officially, because actually it remained an important centre for clandestine teaching and undergroud work on the post-war reconstruction of Warsaw, and acted as the seat of the underground Home Army. In 1939, the head of the Chair was Jan Zachwatowicz, who assumed this post after the death of Prof. Sosnowski. The scientific and patriotic atmosphere of the Chair was cultivated for many postwar years. Wojciech Kalinowski, who commenced his scientific career here, retained the attitude moulded by the Chair up to the very end of his activity.