The socle stones of the Great Temple in the Lower City of the Hittite capital city, Hattusha (??orum Province) have been studied for the first time by petrographic and geochemical analysis (Sr isotope, stable isotope, and trace element geochemistry). Study objectives were to determine the carbonate facies of the stone samples used in the Great Temple and investigate their possible sources. Petrographic analysis of 10 limestone samples presents five clusters of different microfacies. Stable isotope (??13C and ??18O) analysis displayed the presence of 5 groups in parallel with petrographic analysis. Trace element analysis of the same groups displayed considerable difference among the stone samples and 87Sr/86Sr isotope ratios change between 0.70697 and 0.706867. Based on the results, it can be stated that the building using stones are from probably five different sources. This is of great importance to better understand the construction process and the acquisition of the building materials.