Masonry stands out as one of the most widely employed building materials globally. Various sources indicate that around 70% of the world’s-built environment relies on masonry [1]. Despite its numerous merits, masonry structures, particularly those deemed cultural and historical heritage, exhibit a significant drawback in terms of seismic vulnerability [2]. The poor tensile strength of masonry renders these structures susceptible to horizontal forces. This vulnerability is understandable given that many of these buildings were constructed prior to the establishment of sufficient seismic regulations. The most vulnerable parts of these buildings are located at openings. Therefore, masonry piers that may be defined as structural elements between windows, are considered one of the most vulnerable elements in an unreinforced masonry building when subjected to horizontal actions. To better understand the behaviour and the problems that may occur in unreinforced masonry piers, a proper evaluation is conducted in this paper. First, an experimental campaign is conducted with three full scale samples of URM piers. The experimental campaign is a quasi-static displacement-controlled testing protocol where the main results are the initial stiffness, maximum displacement, and maximum in-plane horizontal force in the negative and positive direction of URM piers. To check the quality of the results, a numerical model is developed in DIANA FEA software. A micro-modelling approach is chosen for the most detailed analysis of the pier's behavior. From the comparison of the results, it is clear that the URM piers are vulnerable to horizontal actions. Additionally, it is observed that the results gathered from the numerical modelling are a bit conservative in regards to the experiment. And even though these results are a bit conservative, it is concluded that a micro-modelling approach gives an adequate representation of URM piers behavior. In the end, comparisons will be drawn, and conclusions will be provided on the behavior of URM piers and seismic actions. REFERENCES [1] A. Drougkas, L. Licciardello, J.G.Rots, R. Esposito In-plane seismic behavior of retrofitted masonry walls subjected to subsidence-induced damage, Engineering Structures, 223, 2020. [2] G. Barbieri, L. Biolzi, M. Bocciarelli, L. Fregonese, A. Frigeri Assessing the seismic vulnerability of a historical building, Engineering Structures, 57, pp: 523–535, 2013.