In the strategic X Regio, a border region of the Italian peninsula, the Romans made the first connection between the Latin and the Germanic world, the Via Claudia Augusta, which went up from the Adriatic to the Danube.

Initially created as a route of conquest and defense, the road was completed in 46 AD by emperor Claudius Augustus with different aims: it had to favor the exchange of goods and knowledge with the Germanic area, contributing to a civil development.

However, given its strategic position – as a stronghold for possible incursions from the north – several castrums were erected along the road, namely wooden and stone fortifications that served as a camp for the legionaries and fixed forts for the control over the land.

In the most upstream part of the current site where CastelBrando stands, one of particular importance was erected, with 2/3 m thick walls about 30 m high, which according to assessments housed about 200 soldiers.

The castrum was equipped with prisons and roman baths, whose remains are still visible today in the Spa area of the castle.
During the archaeological excavations, in the courtyard appeared the ancient pipelines that, through an ingenious hydraulic system, took water from 3 very pure sources, which still feed the castle today.
Another remain of the castrum still present at CastelBrando is the well well-kept roman oven.

In medieval times, the stones of the castrum were finally used to erect the main tower of the castle.