<p>Cáceres, a small city located in the westernmost part of Spain, is one of the best-preserved historical urban ensembles in Europe. Its historic centre, designated a World Heritage Site by UNESCO in 1986, is encircled by a defensive wall dating from the Almohad period in the twelfth century. Due to the continuous exposure of this ancient rampart to weathering agents, it is necessary to establish criteria for its prevention and restoration, based on the knowledge of the materials used in its construction. Although there are some detailed studies on the building materials used in this historic structure, they are insufficient to provide a comprehensive description of all the materials used in this building. Geomaterials, both artificial and natural, are the most widely used building materials in the construction of architectural heritage. Mortars are one of them. The objective of this study is to characterise the mortars used in the Almohad wall of Cáceres, Spain. To this end, a rigorous sampling procedure was conducted in areas containing original archaeological remains, with subsequent analysis through optical microscopy, X-ray diffraction, thermogravimetric analysis, and mercury intrusion porosimetry. The results obtained from this study indicated that the mortars were manufactured using lime as the binding agent, with local geomaterials such as granites and quartzites fragments as aggregates. These findings, consistent with those of other historic mortars, facilitated a more comprehensive understanding of the mortars used in this building, providing relevant information to develop new compatible mortars for future restorations, and filling the existing gap in the building materials employed in this ancient wall.</p>