Abstract
This study analysed the results of the joint research into the building materials of the historic masonry of the retaining wall of the Gediminas Castle Hill dating back to the end of the 13th and beginning of the 14th centuries. Core samples for material testing were collected along the entire height of the retaining wall to assess its load bearing capacity. Boreholes were drilled 600⁻1000 mm from the exterior of the wall to determine the properties of the ceramic bricks and lime mortar that were not affected by external factors. The analysis of the microstructure and chemical composition, mechanical and physical properties of the ceramic bricks and lime mortar is presented. The high compressive strength (8.5 MPa) of the lime mortar was the result of using hydraulic lime and crumbs of ceramic bricks as mortar aggregate.