## 3 Proposed Methodology
### Step 2: Materials Characterization and Mechanical Characteristics  
Among the crucial tasks for a successful modeling of masonry structures is that referring to the characterization (physical and mechanical properties) of the building materials. Furthermore, in the case of monumental masonry structures, both the characterization and the properties of materials such as stones, bricks and mortars are critical for the structural modeling of the structure. When dealing with historic masonries, the researcher must keep in mind that the structure in its current state, as well as the materials comprising it, are disturbed systems, which have been in service for centuries or even millennia under real mechanical and environmental loads [54]. Thus, the historical building materials comprising it, as well as their characteristics, are a projection of the material that was applied. Characterization of the historical materials, as well as diagnosis of their decay, is crucial to obtain input data necessary for the evaluation of the monument's response in its current state, as well as to select new compatible and performing restoration materials that will serve adequately in relation to the mechanical stresses they are subjected to and be durable in relation to the environment factors negatively affecting them. Analysis of the historical building stones can provide interesting information regarding historical aspects, in relation to quarries exploited during the construction of the masonry, transport routes of the era, methods of material transportation, etc. Furthermore, the study of their decay is a useful tool regarding the durability of different types of stones under environmental loads, as they have withstood natural ageing; therefore, their state of preservation is an indicator of their durability under the specific loads. New stones can be selected through a compatibility assessment of the historical stone with today's quarry stones, regarding mineralogical composition (X-ray diffraction measurements and petrographic analysis, aiming to the highest possible similarity in relation to crystalline compounds), mechanical strength (where the mechanical properties of the new stone, compressive strength, flexural strength, tensile strength, modulus of elasticity, etc.) must be as close as possible to the historical stone in order to ensure that no damage is inflicted on the weaker material), microstructural characteristics and thermohyric behavior (i.e., through mercury intrusion porosimetry, which measures the microstructural characteristics of materials, and capillary rise tests, which provide the capillary rise coefficient of the materials and reveals how water is absorbed from the underground and neighboring materials, where similar values are necessary in order to ensure homogenous moisture transfer and avoid preferential moisture accumulation). The same applies when bricks are used as main building elements or in combination with stones, however in the case of bricks, as they are artificial materials and not natural, the aim is to uncover their production technology (for example, raw materials used, firing temperature, etc.) and try and reproduce bricks of similar mechanical and physicochemical characteristics. Mortars are a complex material, constituted of different materials. Analysis of the historical mortar can provide archaeological information regarding the materials and production technique employed [55; 56], while analysis of its constituents can provide information regarding the provenance of the historical raw materials used with further archaeological implications and discoveries [49; 57]. Typical investigative methods for the characterization of historical mortars--mineralogical and chemical--were analyzed to a great extent by [PERSON] et al. [58; 59].