In a flat field of open pasture in County Kildare, an Early Christian monastic enclosure survives in a form that is easy to miss entirely. The site is roughly circular, with an estimated diameter of around 250 metres, but its defining feature, a shallow fosse or ditch, is only about 20 centimetres deep and four to six metres wide along the arc that remains visible to the north-east, east, and south-west. The interior is covered in cultivation ridges, bisected by a modern field wall, and contains what may be a later medieval field system of small rectilinear plots. The physical remains, in other words, are subtle to the point of near-invisibility, and yet what they outline is a significant early ecclesiastical foundation.

The monastery was founded by Beoán of Feighcullen, one of seven sons of Neasán, who belonged to the Uí Fhaoláin, a branch of the Uí Dhúnlainge dynasty that held considerable power in north Leinster. His feast day, the 8th of August, appears in the Martyrology of Tallaght as that of 'Beoain mic Nessan i Fidh Cullend', and an early seventeenth-century list of Kildare churches records him as bishop at this site. An Ordnance Survey letter cites a Calendar entry naming him 'Beoan MacNeasain Espog ó Fiodhchuilinn in uibh Faoláin', meaning the bishop from Feighcullen in the territory of Uibh Faoláin. By 1568, an Elizabethan inquisition records the place as a rectory, suggesting that whatever remained of the early monastic identity had long since been absorbed into the parochial structure of the established church. Local tradition further placed a holy well in the townland on the site of the monastery, a common echo in Irish landscapes where the memory of early religious activity is preserved in water rather than stone.

The nineteenth-century parochial church and its associated graveyard now occupy the western limits of the old enclosure, a layering of Christian use across more than a millennium that is itself a kind of quiet continuity. The fosse, where it can be traced, is best appreciated from aerial photographs taken in 1966 and 1967, in which the faint circular outline reads more clearly against the cropmarks and ridge patterns of the surrounding ground.