48 Axis of Symmetry as an Expression of Open Unity in Baroque Church Ensembles of the Grand Duchy of Lithuania Kostas Biliūnas Introduction Symmetrical composition in historical architecture is usually considered an elementary and taken-for-granted norm – like our own symmetrical body, the bilaterality of which is usually not reflected upon. the mirror-like correspondence between the left and right sides of a building can be found in all epochs, but it was in the Baroque period that symmetry began to be given special attention. symmetry as a principle of building structure was also applied to the organisation of the surroundings of sec- ular and sacred buildings. in contrast to Baroque parks or urban structures, the importance of symmetrical composition in Ba- roque church environments has been studied in a fragmentary way, and in the context of the Grand Duchy of lithuania 1 prac- tically no attention has been paid to this compositional principle. the goal of this article is to use an architectural theoretical ap- proach to investigate the phenomenon of the bilateral axis of symmetry as the dominant compositional principle in Baroque church architecture and to determine how this principle can be manifested in the surroundings of the Baroque churches of the GDl. the objectives of the article are: to relate symmetrical ar- 1 the abbreviation GDl is used in the rest of the article. Kostas Biliūnas is an architect and a doctoral student at Vilnius Gediminas technical university. His area of interest is high Baroque architecture in the Grand Duchy of lithuania.