Palazzo Fagnoni is the headquarters of “Autostrade per l’Italia” in Florence. The analysis carried out on the building obserbev that the building does nto comply with the italian standard NTC-08 . The designer ha schosen the strategy of the seismic isolation at the base of the building in order to keep the continuity of the work activities in the offices and to preserve the building’s valuable architecture. The special kind of retrofit adapted was to make the base isolation on the bulidng but to increase the gap of the architectural joint between the two later building with the central one.