## 2 Building Characteristics  
The historic buildings of the Bay of Kotor, as well as the wider surrounding area, are usually masonry, massive, nonframe, made of stone as the basic building material and lime mortar as a binder. Masonry structures are affected by significant seismic forces in proportion to their mass. They are insufficiently resilient to tensional and shear stress; they have low ductility (plasticity) and relatively small capacity for stress redistribution. However, the seismic resistance of these buildings may vary to a large extent, depending on the soil and the method of foundation, architectural form, the original quality of their structural elements and construction techniques, maintenance methods and so on. It is difficult to determine to what extent the old builders intentionally designed the structures to be aseismic both regarding the entire structure and its elements. Nevertheless, it is evident that, in the overall construction process, they primarily took into account the structural load and general safety of the building and often achieved extraordinary results from the aspect of their earthquake resistance. Regardless of whether the entire structures or their individual elements had originally been intentionally designed as earthquake resistant, it is important to understand their role and contribution to the favourable behaviour of the building during an earthquake. Gaining an insight into the original seismic properties of architectural heritage would contribute to having minor interventions and more rational solutions for their structural rehabilitation, that would, among others, be beneficial from the aspect of preserving the original structural assembly as the essential feature of historical buildings whose authenticity is particularly valued. The continuous uniform distribution of stress is closely related to the stated properties of architectural form: symmetry, simplicity and regularity. It has been proved that buildings, having their load-bearing structural elements evenly distributed, with continuous walls without abrupt changes in thickness, have the maximum chance of surviving an earthquake. The axial arrangement of the openings and vertical strips of walls between openings along the entire height of the building are also essential. Any disturbance of the full--empty relationship on the floors would lead to unwanted damage. Such examples are far more uncommon in traditional buildings than in modern ones. It is particularly interesting that with regard to the earthquake-resistant properties, the openings in the walls (doors, windows) were the subject of special attention of the old builders. Segmental or flat relieving arches or somewhat simpler arches on three joints were usually placed above the window sills and lintels. Vaults and arches were among the frequently used constructive elements. Some of them, especially those precisely carved of stone from the Durici quarry, with narrow joints and raised lanced arches, are extremely good aseismic structures, which was proved by their stability in earthquakes, including the latest one in 1979 (Figures 1 and 2) [8]. These masonry buildings represent a box-type structural system composed of vertical structural elements--walls--and horizontal structural elements--floors and roofs. Vertical loads are transferred from the floors, acting as horizontal flexural members, to the bearing walls, and from the bearing walls, acting as vertical compression members, to the foundation system. The most common technique uses \"cornerstones\", stones of a larger size than those used in the walls and typically of regular shape. Effective coupling of orthogonal directions through the thickness of the walls is possible. Also, the efficient system of restraining building walls to maintain the box was made with wooden or iron chaining.