The year 2022 witnessed the finding at the Faculty of Architecture of the Warsaw University of Technology of negatives consisting mainly of to date completely unknown photographs from the years 1935–1939 whose author was most probably Szymon Syrkus. What was ascertained was that out of approximately eighty surviving photographic plates, most pictures were of formal and informal meetings of members of the International Congresses of Modern Architecture (CIAM) that took place over the years 1935–1937 as well as historic and contemporary buildings visited by Helena and Szymon Syrkus during their foreign and domestic, business and private trips. The smaller part of the discovered plates, encompassing approximately twenty plates—no less important for researchers into Interwar Modern architecture—are photographs documenting the course of construction and the architecture of three residential buildings that over the years 1938–1939/1943 were wholly or partially designed and built in Warsaw by leading architects of Poland’s Interwar Avant–garde—Helena and Szymon Syrkus. These photographs not only enrich our knowledge on the Interwar design work of Helena and Szymon Syrkus within Warsaw, but also provide much information relating to the structural and material solutions they applied as well as the aesthetic and standard of finish and furnishings of the dwelling units they designed.