Most of the buildings in many mountain regions in Bulgaria were built during the first half of the last century of non-standard building materials – stonemasonry, adobe brick masonry, etc. The seismic behavior of such structures is unknown, and occupation of the buildings is dangerous. This paper offers an experimental methodology for assessment the seismic behavior of one-bay one-story masonry non-engineered buildings and options for their constructive remediation to improve the seismic stability of the latter. The sequence of the proposed methodology is the following: Architectural structural modeling of the investigated building, approximate numerical studies in the environment of software packages for dynamic analysis of structures, construction of an experimental scale model of the building, experimental study of a built scale model of the building, constructive reinforcement of the model, experimental study of the structurally reinforced model. Architectural modeling is based on on-site photography. Approximate numerical studies are in the SAP2000 environment. Harmonic excitation is applied to the experimental model, made on an approximate scale of 1:5, and the vibration forms and their corresponding frequencies are experimentally determined. The seismic behavior of the structure is evaluated based on the obtained first resonance frequency. After the study, the model is structurally reinforced with a horizontal, vertical, or mixed structural system and is re-tested. Based on the difference in the first resonance frequency, the improvement of the seismic behavior is evaluated.