According to legend in the eighth century BCE, Romulus the founder of Rome sent his commander Camulio to capture his nephews Aschio and Senio. Camulio set up his camp here and the place took his name, now changed only slightly to Camollia.
It was always the best defended of all Siena's gateways because of its position facing via Cassia leading directly to Florence. The villages in the area joined together around the first millennium to form Camollia, and it is from this date that there is a record of a fortified gateway. The gateway seen today was designed in 1604 by Alessandro Casolani and decorated by Domenico Cafaggi. An inscription on the exterior arch records the entry of Ferdinand I into Siena: ''Cor magis tibi sena pandit'' (Siena shows a heart that is bigger than this gate).