As a result of the increasing demand for the condition assessment and rehabilitation of historic structures, the application of modal analysis techniques to large-scale masonry buildings is a growing area for the field of experimental mechanics. Although a large body of literature discusses testing on various forms of laboratory specimens, modal testing on a large-scale historic masonry structures has completely different practical issues that challenge the selection of testing variables, equipment, and set-up. Recently, the reading room masonry domes of the State Education Building were subject to experimental modal analysis to enhance the quality of the numerical model. The purpose of these experiments is to identify the dynamic parameters of the vaulted structure and to justify two modeling assumptions established during the finite element analysis: masonry behaves as a linearly elastic material under existing loading conditions, and the construction imperfections have minimal influence on global behavior. The paper also shows that the use of experimental modal analysis can be extended to the investigation of the dynamic interaction between adjacent components of a large-scale structure and to the examination of the elastic support conditions exerted by the adjacent elements.