Hampshire tribes of northeastern Gaul - whether these two events are linked to the decline of hillforts is unknown. By the Roman conquest, the "oppidum" at Venta Belgarum, modern-day Winchester, was the "de facto" regional administrative centre; Winchester was, however, of secondary importance to the Roman-style town of Calleva Atrebatum, modern Silchester, built further north by a dominant Belgic polity known as the Atrebates in the 50s BCE. Julius Caesar invaded southeastern England briefly in 55 and again in 54 BCE, but he never reached Hampshire. Notable sites from this period include Hengistbury Head (now in Dorset), which was a major
Venta Silurum Roman temple, perhaps dedicated to Mars and the Celtic god Ocelus, have been identified on the site. A bowl with a chi-rho symbol shows that the worship of early Christian worship had begun in the late 3rd century. Following the withdrawal of the Roman legions from Britain, the town remained occupied until at least the mid-5th century. Early Christian worship was still established. The town might have had a bishop. A monastery was founded by Saint Tatheus in the 6th century. The site of the present church occupies part of an early Christian cemetery. The name "Venta" gave its name