What emerged instead was the ghostly outline of a settlement that had been invisible to every previous investigation, including a geophysical survey carried out in 2005 that had detected nothing at all. The site had spent centuries hiding in plain sight, erased above ground, preserved below it.

Archaeological monitors Liza Kavanagh and Barry Lacey, working for Irish Archaeological Consultancy Ltd under licence 19E0194, recorded a total of 133 features of probable archaeological significance across the Phase 5 area of the Tower Homes development. The most substantial of these was a large, slightly oval enclosure, approximately 50 metres along its northwest to southeast axis and 45 metres across its northeast to southwest axis, straddling both stripped fields. A ringfort, in the Irish early medieval context, is a roughly circular enclosed farmstead, typically defined by one or more earthen banks and ditches, and they were built and used from roughly the fifth to the twelfth century. This one had been levelled so thoroughly that it left no surface trace, yet the ditch circuit survived underground, complete with a causewayed entrance, a gap in the ditch approximately three metres wide, positioned to the east-southeast. Around 22 pit features were identified within the enclosed area, their relationship to the main enclosure still uncertain at the time of recording. A ferrous object retrieved from the ditch fill, combined with the enclosure's siting on level, raised ground overlooking a watercourse and valley to the northeast, pointed the excavators firmly towards an early medieval date. Scattered across the wider area were pits, possible hearths, post holes, stake holes, and what may have been kiln features, suggesting activity well beyond the enclosure itself.

What makes the Monalin site particularly striking is how thoroughly conventional field history had concealed it. Examination of both the first and second edition Ordnance Survey maps showed only undivided pasture, with no hint of earlier boundaries or features. Even a dedicated geophysical survey fourteen years before the monitoring work found nothing. It was only the physical disturbance of construction, watched by archaeologists who knew what to look for in the soil, that brought the enclosure back into view, if only briefly, before development continued around it.