Mario Primicerio, former mayor of Florence and an internationally recognized mathematician, died at the age of 85. Over the years, he was a member of the National Academy of the Lincei, president of Industrial Innovation through Technological Transfer, and of the Italian Society for Applied and Industrial Mathematics. Primicerio was a notable intellectual who was drawn to politics. He was a scientist who devoted a significant portion of his life to the advancement of peace. The 1965 mission to Hanoi, the capital of North Vietnam, alongside Giorgio La Pira, despite its failure, remains a significant milestone in the annals of "bottom-up" diplomacy - one of many global efforts he participated in. Primicerio saw his election as mayor of Florence in 1995 as a natural continuation of his devotion. Throughout his tenure, Florence was the site of a plethora of cultural, international, and institutional initiatives that were designed to fortify its status as a hub for dialogue between religions and peoples.