||Historical structures are among the remains of our rich cultural heritage. They should bevalued and well preserved. The typical historical structures is very rigid. Consequently, theyhave important enemies; foundation problems and earthquakes. Such structures beingcenturies old, they have gained equilibrium of soil-foundation-structure interaction, so nosupport movement is to be expected. However, earthquakes still pose an everlasting danger,as they have destroyed so many historical structures in the past.How safe is a historical structure under a major credible earthquake? This question can beanswered by determining the load effects on the structure and the strength capacity. The ratioof strengthlload effect will yield a quantitative safety factor.The dynamics analysis of the three dimensional structure is performed. Then, the structure isdiscriticized to single out the vulnerable elements. The arches and piers Seem to be theelements most susceptible to failure. The strength interaction diagram are developed betweennormal forces and moments for the vulnerable piers and arches. Thus, the factor of safety forthe total structure can be determined.The method of analysis has been applied to Mihrimah Mosque of Master Architect Sinan(1565). The results show that the piers and arches are very safe under own weight, the factorof safety being in the range of 56. Under the credible earthquake, the factor of safety isreduced, but still adequate as 2-3.