That detail alone signals the kind of place this is: somewhere the sacred and the everyday have been rubbing against each other for well over a thousand years. The roughly circular enclosure that surrounds the church and graveyard, measuring some 62 metres across, may preserve the original boundary of an Early Christian monastery, its earthen bank still standing around 70 centimetres high along the western half, with granite stone facing added at a later date. Scarps cut into the ground on the north-east, east, and south sides mark where the earliest perimeter ran, visible as abrupt drops in the terrain within the present graveyard.

The monastery here was founded in the sixth century by St Finnian of Clonard in County Meath, and the place-name preserves a story attached to him. His Life records how a man named Muiredach gave Finnian a field that his son Bresal had refused to grant. Finnian improved the land, and it became known as Achad Aball, meaning Field of Apple-trees, the origin of the modern name Aghowle. The same text adds that Finnian lived at the site for sixteen years before an angel told him it was not to be the place of his resurrection, though it would be the place where he would meet his monks on the Day of Judgement. That eschatological promise is attached to the nearby mountain, called Sliab Condala, from the Irish word comdál, meaning a meeting or assembly. The annals record the deaths of Cormac Ua Mithidhein, abbot of Aghowle, in 1015, and Diarmaid Ua Cele, erenagh of Tullow and Aghowle, in 1050; an erenagh being a hereditary church official responsible for managing ecclesiastical lands. A Romanesque church, that is, one built in the rounded-arch style common in Ireland from roughly the twelfth century, still stands in the eastern part of the graveyard. In the north-west quadrant stands St Finnian's high cross, and 100 metres to the south-east lies an earthfast bullaun stone, a granite boulder with one or more hollowed depressions, a type found frequently at early monastic sites across Ireland. A wedge-shaped cross-slab, recorded in 1925 as bearing a Greek cross within a circle on one face and a human face on the other, had not been located as of 2011.