Portheras Barrow stands on Portheras Common near St Just in West Penwith. It is one of the larger surviving prehistoric burial mounds in the area, measuring about 40 feet across and 2.5 feet high. Much of its stone kerb still survives, showing the outline of the original mound. At its centre is a well preserved cist, about 4 feet long and 2 feet wide, covered by a large capstone around 6 feet across. The barrow lies within a landscape rich in both archaeology and natural history. Portheras Common forms part of a Site of Special Scientific Interest and contains a mixture of open ground, vegetation, and ancient remains. The monument can be difficult to see in summer when the vegetation is high, but its survival makes it an important part of the prehistoric landscape around St Just. West Penwith contains many barrows, cairns, chambered cairns, and entrance graves, reflecting a long tradition of burial and ceremonial activity. Portheras Barrow belongs within this wider pattern of prehistoric monument building. These sites were not only places for the dead, but also visible markers in the landscape, connected with ancestry, memory, and community identity. Their positions often suggest careful placement within the surrounding hills, fields, and coastal routes. Portheras Barrow was excavated in 1891 by the antiquarian William C. Lukis. The excavation produced pottery, flint tools, and human bones. These finds suggest that the barrow was used for burial and may also have had a wider ritual function. The presence of human remains indicates a connection with ancestral commemoration, although the exact nature of the practices carried out here remains uncertain. Today, Portheras Barrow remains a valuable archaeological site and part of the wider prehistoric landscape of West Penwith. Although parts of the original chamber have been lost, the surviving kerb, cist, and capstone still give a clear sense of its original form.