This study aims to evaluate the seismic vulnerability and guide the restoration of a historic masonry complex in Naples, soon to become the new venue for the School of Fine Arts. Given the complex’s rich historical and cultural significance, the restoration approach prioritizes both structural and architectural integrity. To assess seismic vulnerability, this study employs the simplified mechanical model from Evaluation Level 1 of the Italian Guidelines for the Assessment and Reduction of Seismic Risk of Cultural Heritage. This approach provides a preliminary analysis of the building’s structural health, identifying seismic safety indices, main vulnerabilities, and potential collapse mechanisms. The restoration process includes a comprehensive analysis of original materials and construction techniques to develop compatible consolidation strategies that respect the historical context. Innovative reinforcement solutions were integrated to improve seismic resistance while preserving the building’s authenticity. Key interventions include reinforcing masonry walls and vaults and implementing measures to achieve a unified “box behaviour” for the entire structure. Overall, this work makes a valuable contribution to preserving cultural heritage, supporting its adaptation to new uses, and ensuring safety for future occupants.