Discussion of the methods of testing samples from the relics of foundations and walls belonging to ancient and early-medieval buildings. Tests embrace macroscopic, chemical, and quantitative (planimetric microscopy) analyses to help determine composition and types of mortars and fillers used. Polarization microscopy, and in some cases electron scanners as well, have been extremely helpful in identifying the structure, texture, and degree of carbonization of lime mortars, as well as the type and character of particular components. Physical and mechanical tests have enabled the researchers to evaluate whether mortars are in a good state of preservation or not. Differential thermal analysis has helped in distinguishing dihydrous gypsum from the semihydrous one, calcium carbonate from dolomite, and in assessing the percentage of claylike minerals and organic substances. Investigations carried out with said methods on mortars from Wislica (8), Wawel Castle of Cracow, Kije, from Alexandria and from the Pyramid of Cheops have shown how diverse these mortars are -- lime mortars, lime-andgypsum mortars, gypsum mortars; and have also brought to light high variability in the contents and in the type of particular filler ingredients. See also AA TA 8-1491 and 10-367.