“…The elaboration of the research is based on the identification of certain issues arising from the topic and the study of related sources. Within the framework of the literature, in particular, the issues were considered in the following directions: interrelations between structural and artistic solutions in architecture [1,[11][12][13][14]; general issues of ensuring the strength of structural systems and work efficiency [15,16]; issues related to masonry and its structure [17][18][19][20][21]; questions about the composition of the core in three-layer walls, binding materials and their development, differentiation of the core, as well as its effect on masonry and overall structure [12,16,21,22]; measures to ensure structure unity of the three-layer wall in Roman, Byzantine, and Syrian structures [12,13,[23][24][25][26][27][28]; the process of gradual evolution of three-layer walls in Armenia [29][30][31][32]; peculiarities of "midis" masonry, the composition of its core, its homogeneity and monolithic nature in the structure of the structural elements [30,31,33]; general description of the structure of Armenian medieval churches [33][34][35][36][37][38][39] and typological classifications [30,…”