Penventinnie Round is a prehistoric enclosure north west of Penventinnie, near Truro. It belongs to a wider group of monuments known as rounds, which are found across parts of the British Isles but are especially characteristic of Cornwall and south-west Devon. More than 750 are recorded, many of them around the Irish Sea region. In Cornwall, rounds are a major source of evidence for understanding settlement, farming, defence, and social organisation during the Iron Age and Romano-British periods. Rounds are usually enclosed settlements defined by an earth bank and an outer ditch. They are often positioned on hillslopes, spurs, or naturally defensible ground, giving their occupants visibility across the surrounding landscape. Some may have held farmsteads or small communities, while others may have had wider social, defensive, or ceremonial roles. Sites with substantial surviving remains are often considered nationally important because they can preserve buried evidence of buildings, occupation layers, entrances, ditches, and daily life. The Penventinnie example is a well preserved near circular defended enclosure, positioned just below the summit of a north-facing spur. It measures about 85 metres by 60 metres and is defined by a single earthen rampart up to 8 metres wide and 2 metres high. The original entrance appears to lie on the north east side, while a later break was made on the south west. The outer ditch is especially clear to the north, although it is less visible on the southern side, probably because of natural silting and later disturbance. The site also benefits from its setting. The Kenwyn River and its tributaries enclose three sides of the surrounding landscape, giving the round a naturally strong position. It was not an isolated monument. Several broadly contemporary settlements lie nearby, including rounds at Threemilestone, Higher Besore, Polstain, and Carvinack, as well as the larger hillfort at Bosvisack. This concentration of sites suggests a busy and organised later prehistoric landscape around what is now the western edge of Truro. Penventinnie Round has been recorded for nearly two centuries. It appeared on the tithe map of around 1840 as “Ancient Fort” and was later noted by antiquarians, including MacLaughlan in 1847 and Thomas in 1851. In the early twentieth century, Henderson described it as a “very perfect round” with a thick earth rampart and a well-defined ditch, although some wear was already visible. The Ordnance Survey recorded it again in 1965, by which time parts of the ditch had been ploughed in, and the later south-west gap was noted. The monument was scheduled in 1975, with its designation updated in 1997. Today, Penventinnie Round sits close to the expanding Langarth Garden Village development on the edge of Truro. This places an ancient defended enclosure beside one of Cornwall’s most significant modern housing projects. The contrast is striking, but it also shows how Cornwall’s historic landscapes continue to exist within areas of growth and change.