The research methodology uses a combined strategy, interpretative historical and qualitative, as a systematic and comprehensive approach to the study. The historical design provides analysis and synthesis of collected bibliographic and archival materials on two topics: evidence of Perret’s work in Poland (copies of pages of Perret’s treatise in Polish and Ukrainian archives and other related archival materials) and documentation of built examples that follows Perret's models (drawings, photographs, maps, and cadasters). The qualitative component will be based on the typomorphological comparison of Perret’s models and built examples. The typomorphological analysis includes a novel interdisciplinary approach to such topics. It is based on creating simplified 3D models and their analysis using Rhinoceros 3D software with an Add-on called Grasshopper. This software will be used to analyze the proportions of each case study's part: civil and military. Also, using the same software, it is planned to make a spatial analysis of case studies based on Hiller and Hanson's theory of space which proved to be very helpful for understanding the bastion castle structure in preliminary studies.