The Roman city of Venta Silurum was founded around 75 AD in the lands of the conquered Celtic tribe of the Silures. In the early period of existence, it did not have any fortifications yet, in order to erect it, it needed a imperial permit, which for the newly conquered peoples was not granted. The first timber and earthly fortifications were built until the end of the second century AD. The reason for its creation is unclear, because Venta Silurum was an administrative center, not a military one. Some historians say they were built for prestige purposes or to facilitate tax collection, but it seems more likely that they were raised in response to an external threat in the form of Irish pirate invasions. Around 290, the 2nd Augustus legion was withdrawn from nearby Caerleon. With the increase risk of raids, it became an impulse to build a stone wall and stone towers fifty years later. In the 11th century fortifications were still functioning, as they were used by the Norman invaders to build a timber watchtower within them. In the following centuries they were certainly too large for the dilapidated town and gradually turned into disrepair.
The first fortifications consisted of a V-shaped ditch and rampart. The latter was built from earth, dug out during trenching and reinforced with wooden stakes for stability. It was topped with a palisade, and four timber gates led to the town, one on each side of the world.
Stone fortifications created at the turn of the third and fourth century, consisted of a wall with a height of 7 meters. Fifty years later, it was reinforced with a row of polygonal towers protruding from the face of the wall. They were open from the town side and had a timber platforms at the top for the defenders. Probably along with the wall they were equipped with a battlement. The towers were added only on the northern and southern sides of the town (6 on the south side, 5 on the north side). A new, second ditch has also been added, to account for the increased height advantage, that the defenders had with the new fortifications. The elder ditch was filled up at that time. Four gates have also been rebuilt into stone. It consisted of two towers flanking the passage between them.
In the 11th century, in the south-east corner of the walls, a mound was erected by the Normans, on which a timber motte and bailey castle was located. The mound was topped with a palisade and protected on both sides by Roman walls and by an old double system of dry moats.
The town walls in Caerwent, preserved to the present day, are one of the most impressive Roman monuments in Great Britain. In the best condition they survived on the southern side of the town, where they are visible from the east to the west along their entire length. In the best-preserved places, they reach a height of 5 meters. The lower parts of some of the towers and the mound on the south-eastern side on which the Norman castle stood, also survived.
Website castlesfortsbattles.co.uk, Caerwent roman town.
Website gatehouse-gazetteer.info, Caerwent town walls.