This work stems from an extensive campaign of localization and surveying of historic masonry walls in Opus Reticulatum, found in the Campania region. Surveys were conducted at significant sites such as Pompei, Herculaneum and Paestum. The primary aim is to typologically define the masonry walls, identifying common characteristics in terms of texture, dimensions, and materials. The prototype test walls, replicated according to the collected data, are analysed by micro-mechanical Finite Element models to provide a preliminary understanding of the mechanical behaviour under axial and diagonal compression. The micro-modelling procedure involved the definition of the mechanical behaviour of the mortar, the bricks and the stones. Model parameters were calibrated using limited experimental test results available in literature on individual components of the masonry. This research wishes to contribute to a deeper understanding of historic masonry structures and lays the groundwork for further investigations.