This article presents a description of Olsztyn from December 1947 – the most extensive developed in the first post-war years and preserved in statistical studies of the city. The document is stored in the resources of the State Archives in Olsztyn. It was drawn up by the City Board for the planning of the inspectorate of the Voivodeship Office in the context of individual administrative units at the district (powiat) level, whilst at the same time constituting comparative material in the activities of the Ministry of Regained Territories. The collected material contains data on various sectors of economic and social life in the capital of the then Olsztyn province (general location, area, population, sex, nationality, age, religion, employment, war damage and reconstruction, the state of industry and trade, agricultural issues, healthcare and social assistance, education, culture and arts, religious issues, communication, hydrology and meteorology, public safety, administration and its structures, etc.). From a contemporary perspective, the analysis and verification of the information presented in the description – showing the actual condition of the city and the living conditions of its inhabitants seven decades ago – provides a useful source for further research on the infrastructure of urban centres in Warmia and Masuria after the end of World War II.