On the rationale behind the design of side vestibules in Eastern Christian churches

The article is devoted to establishing the reasons for the emergence of a Christian church with three vestibules, which is not possible without answering the question about the reason for the presence of side entrances to the liturgical space of the interior. The symbolic understanding of the church space in the 7th–10th centuries underwent a transformation from the cosmological model «Church – Space» to the model «Church – «earthly heaven»» (according to G. K. Wagner). The New Jerusalem from the Book of Revelation is considered as a specific spatial image of the Christian Heavenly World, which became the basis for the architects of the «earthly heaven». A church building with three separate entrances is seen as a «spatial icon». Quotes from the Vision of the prophet Ezekiel are analyzed, as well as the opinions of various researchers on the use of geometric forms in a church building opening on four sides. Brief conclusions are drawn about the symbolism of these forms, the anthropomorphization of the plan of the cruciform building, comparisons of iconography and the structure of the space. Studying the works on the history of the Byzantine church rite allows us to analyze the inclusion of the vestibule space in the course of worship. Particular attention is paid to the history of the emergence of a new type of worship in Constantinople in the 4th century, which had a significant impact on the architectural structure of Hagia Sophia in Constantinople. The functional necessity of the side vestibules is analyzed based on the historically formed trajectories of people's movement during the liturgy. Based on a study of bibliographic sources, a hypothesis is suggested about complex reasons that led to the emergence of churches with three vestibules: constructive, iconological, semantic, liturgical, and functional.