To pass it without knowing what it is would be easy enough; it does not announce itself. Yet the geometry is precise and the preservation unusually good, and what it describes in the landscape is a ring barrow, a type of prehistoric funerary monument in which the defining feature is the encircling ditch, known as a fosse, rather than a prominent mound.

The monument measures nineteen metres across its enclosed interior, with the fosse reaching ten metres in width and dropping to a depth of one and a half metres. That is a substantial trench, and its survival in this condition is notable. Ring barrows of this kind are generally associated with the Bronze Age, though they can also appear in Iron Age contexts, and they typically mark burial or ritual activity. The interior here is gently domed but does not project above the general level of the surrounding ground, which partly explains why it reads more as a depression in the earth than as any kind of raised structure. A field boundary runs around the monument from the south-east, curving through south and west to north-west, suggesting that whoever established the modern agricultural boundaries recognised something worth skirting rather than cutting through. There is no clear evidence of an external bank, which in ring barrow typology can sometimes be a meaningful absence, though what it tells us about the original design or later disturbance at Rathornan is not fully resolved.