A previously formulated assessment procedure of the seismic performance of historical and artistic buildings is herein applied to a representative example of the eighteenth-century noble-residence architecture in Tuscany. Differently from other examined case studies, where essentially elastic structural models had been used, the analysis of the current status of the building is carried out in this case by a non-linear smeared crack model. As a general result of the evaluation enquiry, no limitation relevant to the three postulated performance levels is met for the corresponding levels of seismic action. In order to substantially improve the response capacities of the building, an advanced seismic retrofit hypothesis is then formulated, which consists in a combined base isolation/supplemental damping technique obtained by coupling steel-teflon sliding bearings and silicone fluid viscous devices. Finally, this retrofit solution allows largely attaining the established performance objectives.