This study deals with dome of Al-Ashraf Khalil bin Qalawun one of the most important mausoleum domes in the Mamluk era in Cairo. The study pro-vides an architectural description of the archaeological site, an assessment of its current situation by using the modern means for architectural documentation, documentation of damage, and a general perception of the building's condition after restoration work. As well, An archaeometric study of the building materials of the mausoleum and their deterioration aspects was done by the help of X-ray diffraction analysis (XRD), polarizing microscope (PM) and Scanning electron microscope equipped with an X-ray energy dispersal unit (SEM-EDX) This archeometric study revealed that the studied lime-stone consists mainly of micritic calcite and traces of sand as well, traces of Halite, also it revealed the use of lime mortar, finally it confirmed that halite is the main destructive salt of the studied building materials. The mechanical properties of the used limestone were evaluated by measuring its compressive strength. The study determined a scientific plan for rectifying the damage and restoring the deterioration aspects.