Historical buildings are vital imprints of a region’s history and culture, reflecting the heritage of its communities. Nalanda Mahavihara, once a renowned center of learning, continues to uphold its legacy as a UNESCO World Heritage Site. Although its origins date back to the 4th century CE, the excavated masonry structure at the present site remains in remarkably good condition, likely due to careful construction, and/or precise material selection, and the use of specific technologies. This study examines the material properties and construction techniques of historic masonry through physico-chemical, microstructural, particle size, and thermal analyses. Historic photographs were utilized to identify the bonding patterns. The study revealed the use of mud, primarily composed of silt, as bed joint mortar. The bricks were fired at temperatures exceeding 900 ℃ and were vitrified. This study also demonstrates compatibility tests between historic and new bricks and mortar, recreated in the laboratory using modern materials, with the aim of identifying suitable substitutes for conservation and restoration of historic masonry, through an analysis of their pore structure and other material characteristics. Additionally, diagonal shear, and uniaxial compression tests on masonry specimens were performed to evaluate the shear, and axial behavior. The findings will enhance understanding of the material properties and assess the current condition of excavated masonry structure. It will also provide data useful to calibrate failure criteria available for assessing the heritage unreinforced masonry by numerical modelling using FE analysis.