For many centuries, in medieval Serbia and Ancient Russia, Byzantine prototypes were assimilated and processed according to the local conditions and needs. Often the results of those borrowings were similar between each other, which gave rise to hypotheses about the influence of one Slavic tradition on another. In both cases, other foreign influences also played a significant role. Many aspects of the parallel development and connections between these two branches of medieval Eastern Christian culture remain unclear. Meanwhile, understanding the nature of their similarities and differences would allow us to see more clearly the uniqueness of each path.This article attempts to do the analysis of these phenomena by the example of the most striking and final ktitor project of King Stefan Uros II Milutin (1282-1321) monuments, the Church of the Assumption of the Virgin in Gračanica. In the works of Serbian architectural historians, in particular V. Korac and S. Churcic, it is clearly shown that many architectural traditions of the era of Serbian King Milutin go back to specific significant examples of the Byzantine Emperor Andronikos II (1282-1328) reign. These are the churches erected in the late 13th - first quarter of the 14th century in Thessaloniki: the churches of St. Catherine, St. Pantheleimon, Sts. Apostles, and the Catholicon of Vlatadon. However, both the nature of these samples and the methods of their interpretation on Serbian soil are already somewhat different at the initial stage. In this context, the problem of the masters who built on Milutin's orders and the specifics of his plans are also relevant. The article focuses on the analysis of the architectural features of the Gračanica monument, which distinguish it from the group of other churches in Thessaloniki. We have tried to explain the origin of this kind of specificity, which, moreover, finds surprising parallels in the logic of variations of Byzantine patterns in Moscow architecture of the 14th- first third of the 15th century. The identification of similar trends in the history of architecture of the southern and eastern Slavs fascinates even more when it becomes obvious that due to the discrepancies in chronology and the presence of significant differences in the forms of constructive implementation of the monuments, the observed similarity cannot be explained by direct influences on the level of specific samples or masters.