This paper presents the development of an automated cable-driven robotic system designed for sonic inspections of large heritage structures. The system moves a robotic hitting device across a large planar surface, such as a building façade, generating sonic waves by striking it. The surface is divided into a grid, and multiple impacts are applied at various points. On the opposite side of the wall, a reception system, such as accelerometers, captures the transmitted waves at corresponding points. These waves, or sonic rays are used to analyze the inner condition of the structure, for example through the generation of a detailed tomographic image in 2D and 3D. Sonic tomography has significant potential for evaluating the internal composition of heterogeneous materials, such as masonry, commonly found in heritage buildings. These materials present challenges for traditional Nondestructive Testing (NDT) methods due to their irregular composition. Automating the inspection process enhances speed, accuracy, and reduces the human error often associated with manual measurements. This study presents the preliminary results of an experimental campaign conducted at the Bermeja Towers (Torres Bermejas) in La Alhambra, Granada, Spain. These towers, built from rammed earth in the 11th century and modified during the 16th, 20th, and 21st centuries, were inspected using the automated sonic tomography device. The system demonstrated its capability to generate and receive sonic waves, allowing for the differentiation of various materials within the inspected structure.