The main phases of the study are summarized as follow: description of the monument; diagnosis; modelling of the actions, of the materials characteristics, and of the structural behavior; structural analysis; theoretical safety verification; safety judgement; decisions (e.g., operations, extent of the investigations). Safety judgement is the actual main point of the study, a proper balance between theoretical verification and judgements of empirical and intuitive nature being arrived at; their relative weights depending on the credibility and reliability of the choices.