It is, in fact, likely the surviving arc of a large early medieval ecclesiastical enclosure, the kind of roughly circular or curvilinear boundary that once defined sacred ground around an Irish church or monastery. Such enclosures were common in early Christian Ireland, demarcating the spiritual and practical territory of a religious community, and this one appears to have centred on a church dedicated to St Kieran of Saighir.

St Kieran of Saighir, distinct from the more famous Kieran of Clonmacnoise, was the patron of Kells parish up to the Norman Invasion. According to the historian Carrigan, writing in 1905, the Norman arrival prompted a change of dedication; the old patron was set aside and both parish and church were rededicated to the Exaltation of the Holy Cross. The church building itself was probably reconstructed in the 17th century, though it incorporated Romanesque fragments, carved stonework characteristic of the 12th century, from the earlier structure. Miriam Clyne, writing in 2007, identified the probable outline of a large curvilinear enclosure around this site and noted that one portion of it appears to survive as a curving field boundary approximately 90 metres long. It is visible at ground level as an earthen bank, roughly half a metre to just under a metre in height and about two and a half metres wide, running south-eastward from the south-east tower of the outer bawn of Kells Priory, a bawn being the walled courtyard attached to a defended structure, to the north-east corner of what the 1839 Ordnance Survey six-inch map shows as a former walled garden or orchard. That same first-edition map records the boundary line clearly, which is itself a useful reminder of how much landscape history is legible in early cartography even when the physical remains have been much reduced.