The Castle of Gargarasi today "Residenza Antica Flaminia" was built on the edge of the cliff overlooking the valley of the Treia river, not far from the confluence with the Tiber, in the territory of Civita Castellana.
In past centuries its position benefited from undoubted strategic advantages deriving from visual contact with the city and from the control of both the Valle road and the Consolare Flaminia.
The Castle is located right at the point where a majestic viaduct from the Roman era known by the name of "Muro del Peccato" allowed the Flaminia to overcome the difference in height of over 50 meters that separates the Treia valley from the overhanging tufaceous plateau.
Its conformation undoubtedly places it in the context of the medieval era.
The walls, albeit of modest size, are characterized by the presence of a large entrance arch under which the Flaminia road passed.
The structure of the arch is clearly visible in a photo dating back to the end of the nineteenth century together with the ruins of a building, which no longer exists, which appears to be from the Middle Ages.
At the beginning of the seventeenth century, during the pontificate of Paul V, the path of the "Flaminia street" it was definitively modified and the original stretch of the Roman period was definitively excluded from the great road network.
The old route is easily recognizable by the many flagstones of occhialina (leucitic stone) that occasionally emerge from the ground.
In the park of the Residenza Antica Flaminia, next to the castle, you can see the clean cut made in Roman times of the tuff quarry that was used for the construction of the support works of the consular road, the most important of which is the aforementioned Wall of Sin .
In the following period, an environment on two levels was excavated (which can still be visited today), a scheme that refers to the best-known examples of early medieval hermit caves present widely throughout the Roman Tuscia.