Based on an experimental analysis of the cathedral of St. Jacobs in Šibenik and the obtained dynamic parameters, numerical analysis of the construction of the cathedral and the system of tension braces were performed. The introductory sections provide basic information on the construction of the cathedral with details and a historical overview of its construction. Due to unknown parameters, mechanical characteristics of the materials', unknown boundary conditions, and soil stiffness, the numerical model of the Šibenik Cathedral was calibrated. The experimental testing was first analyzed, and the basic dynamic parameters of the structure and the system of tension braces were given. For the sake of simplicity and convenience, tension braces used in the cathedral have been taken as reference and analyzed below to determine the acting forces on the basis of their own frequencies. For the sake of simplicity of the differential equation of transverse oscillations of the beam loaded with longitudinal force, coefficient κ is defined in the literature. Its value depends on boundary conditions and the modal shapes. Firstly, numerical model was created and the calibrated on the basis of the dynamic parameters obtained by experimental testing to determine the applicability and universality of coefficient κ. Comparison of modal shapes obtained from numerical models and field tests was performed. For each of the previous comparisons, an evaluation of numerical model was performed according to the modal assurance criterion (MAC). After the evaluation of numerical model, the value of the coefficient κ and its deviation from the value given in the literature are determined. After obtaining an acceptable deviation of the value of coefficient κ, the forces acting in corresponding tension braces were determined. Based on the existing plans, a numerical model of the cathedral was created. A static and a dynamic analysis were carried out as part of the model updating by associating the mechanical characteristics of the material and determining the natural frequencies and the modal shapes. Firstly, an initial model was created to update the model by varying the modulus of elasticity of the stone, boundary conditions, and the soil stiffness within the limits that cover the frequencies obtained by experimental testing. After determining the values of the modulus of elasticity and the stiffness of the soil, they were obtained on the three numerical models. Each of them was evaluated according to the criterion of modal orthogonality (MAC factor). On the numerical model which achieved the highest values of the MAC factor for the observed modal shapes, a static analysis and a dynamic analysis were performed, considering the effect of the earthquake and its own structural weight. The forces acting in tension braces obtained by experimental testing were compared with the numerically obtained values, and comparison of the tensile forces in the case of the earthquake action in x and y directions was also made. Due to the occurrence of compressive forces due to the effect of the earthquake loading in the y direction, the possibility of breaking the tension by twisting was also checked.