The beginning of the Roman period is when the local aristocracy of this Ibera city signs a pact with Scipio the African, breaking with Carthage, in the last years of the 3rd century BC. From that moment on, the city becomes Free city, being able to maintain the traditional institutions of government but with the condition of having a Roman garrison, and of eventual sending of troops. It is the starting point of romanization of the city, which probably ends in Imperial epoch, when Castulo becomes commune of Latin law.
From this last period is when more remains remain on the surface. At the northwest end of Cerro de La Muela, we can observe the main water distribution tanks to the city, which culminated in the city through an aqueduct that still appreciates its pillars to the north of the walls.
To the south of these cisterns a semicircular hollow is distinguished, with remains of mortar that could have been the seat of the stands of the theatre. From the current Cortijo de Santa, in the direction of the castle, the space is dotted with points of distribution of the water flow to the different areas of the city.
Another area to highlight of the Roman period of the city is the so-called urban Villa of the Olive Grove, located in the central area and eastward of the walled plateau, also highlighting the “mosaic of loves”. This composed of altoimperial period rooms, possibly of public use, related to a hot springs, among which stand out the hipocaustum and several patios of distribution, one of them with a central source that preserves the original pavement of Opus spicatum.
These thermal facilities were used until late period, when remodeling was made as they introduced different rooms in the form of an apse, which led to a transformation of the town as the eastern end of the city forum , possibly associated with religious practices. At this moment the depopulation of the city begins, being proof of it the appearance of intramural burials on strata of the I and II centuries.
Outside the city also appears remains as the Via Augusta that united the Bética with Rome