ABSTRACTMortars collected from the Cheops pyramid, the Sphinx and the Chephren pyramid, all at Giza, Egypt, have been compared with recently found mortars of a cult building of the aceramic neolithic at Nevali üori (south east of Urfa, province Hilvan, Turkey), probably one of the earliest sites of civilization. As methods of investigation thermal analysis, X-ray diffraction as well as analytical scanning and transmission electron microscopy have been used. The egyptian mortars have been found to be primarily made up of gypsum, anhydrite and calcite. The comparative results with mortar of the recently detected temple site at Nevali Con, Turkey, give evidence that the burning or otherwise chemical treatment of limestone as crucial ingredient for the fabrication of mortar has been performed at a very early period (10'000 - 8000 B.C.). In order to further confirm the described findings 14C dating measurements have been carried out. The results of the described studies raise many questions concerning early civilizations and their knowledge of technologies as well as the transfer mechanisms of this knowledge.