ABSTRACT The majority of the existing historical brick masonry buildings and monuments in Iran were built adopting a structural system made of modularly connected Persian arched walls; two piers connected by an arc-shaped spandrel. Previous earthquakes revealed that these structures are highly vulnerable and seismic rehabilitation of them is of great significance. However, architectural character and cultural value of these monumental structures significantly rely on the appearance of the building and its decorative finishing. Thus, any retrofitting method modifying the appearance of the building is unacceptable. During the last decades, centercore strengthening method has been developed for seismic rehabilitation of these structures. This paper presents an experimental and numerical investigation on the in-plane behavior of Persian arched walls, before and after retrofitting by centercore method. For this purpose, using fired clay bricks and gypsum-clay mortar, three arched walls were built and tested under reversed cyclic in-plane loading. The results showed a significant increase in the ultimate lateral resistance and improvement of seismic performance indices including ductility and energy dissipation. Moreover, a three-dimensional nonlinear finite element model using a combined approach of smeared cracks and discrete elements was adopted to investigate the monotonic in-plane behavior of the retrofitted arched walls.