The area where San Vito Romano now stands was already inhabited in the 10th century BC and lay within the territory of the Aequi, an ancient Italic people settled in the upper Aniene valley and the surrounding lands. The Aequi long resisted the expansion of Rome, which managed to subdue them for good only in the course of the 4th century BC.
According to a well-established historical tradition, the origins of San Vito Romano are linked to Vitellia, an ancient Roman settlement mentioned by several ancient authors, including Livy, Pliny the Elder, Suetonius and Stephanus of Byzantium. Suetonius also connects the name Vitellia with the gens Vitellia, recalling a colony of the same name that the Vitellii are said to have defended against the Aequi.
The link between Vitellia and present-day San Vito Romano, however, has not been proven. The available sources and studies have not yielded any certain archaeological evidence that would allow the ancient settlement to be identified with the present-day town. The attribution therefore remains a historical hypothesis, tied to a tradition that has been widely accepted but cannot be regarded as an established archaeological fact.