We present an innovative application of a non-destructive approach for the mechanical characterization of historical masonry structures, based on the analysis of their dynamic response. The proposed approach exploits the extraction of modal parameters to define mechanical features of the structure such as mass, damping and stiffness matrices by means of Operational Modal Analysis, starting from measurements performed by a very promising, expeditious and contactless experimental technique based on radar interferometry. This approach may be very effective for structural health monitoring purposes. In particular, we apply this technique to a historical masonry bell tower with the aim of detecting and consequently solving some of the experimental challenges arisen in some previous experimental campaigns.