Ancient monuments are significant for the cultural identity of countries and they are also very important from economical point of view. There are a lot of environmental damages that affect building materials and monuments. Therefore, the preservation of the monuments has become a vital challenge. Gradual natural destructive factors including freezing and thawing, heating and cooling, salt weathering and acidic rainfall play an important role in destruction of monuments. In this study, for assessment of weathering effects on engineering properties of Hamedan granitic monuments, heating and cooling (up to 600 cycles), freezing and thawing (up to 300 cycles), and salt weathering (up to 50 cycles) tests have been performed. Also, in order to estimate the deterioration of the Ganjnameh inscriptions, four inscriptions were prepared and subjected to heating and cooling (up to 600 cycles), freezing and thawing (up to 300 cycles), magnesium sulfate salt weathering (up to 60 cycles), and acidic rain (up to 1 year time) tests. The results showed that when compared with that of salt weathering, the effects of heating–cooling and freezing–thawing weathering were negligible. Also, deterioration effect of magnesium sulfate on weight loss has been observed more remarkably than that of sodium sulfate. The deterioration effect of sodium sulfate on loss of engineering properties was evaluated more effectively than that of magnesium sulfate. Simulation of the Ganjnameh inscriptions behavior subjected to the weathering tests indicated that deterioration effect of sulfate solution was more effective than that of other weathering processes.