Surveillance and structural monitoring often occur through systems involving point-based sensors and/or periodic checks on potentially representative portions of the structure. This type of approach, ‘point-specific and time-limited’, does not always allow for timely recognition of the onset of mechanisms potentially harmful to the structures themselves and the safety of people. The use of Distributed Optical Fibre Sensors (DOFS) can be a solution to this problem. The proposed study aims to evaluate the potential application of the innovative NSHT (New Smart Hybrid Transducer) in structural monitoring involving DOFS. The NSHT is a strain and temperature transducer whose sensing core is constituted by a single-mode fibre optic wire protected with an armour of composite material. The interrogation technique is based on the phenomenon of stimulated Brillouin scattering. An experimental campaign was performed to assess the in-field functionality of the NSHT as a monitoring system for architectural heritage. The hosting site is the ancient Santa Maria delle Grazie complex, a masonry structure situated in the southeastern part of Ischia Island. Two prototypes of NSHT made using PBO (polybenzobisoxazole) were installed on the south façade made of 5 arches. A load test was performed on the instrumented arch using simultaneously traditional displacement instruments. A FEM numerical model was developed and calibrated on displacement values to interpret, at best, the load test results. The comprehensive evaluation of collected data demonstrated the NSHT’s capability to detect strain variations accurately and highlighted its potential to enhance the understanding of structural behaviour under load.