Lios an Aifrinn, the ringfort of the mass, suggests that at some point after the early medieval period, when these earthwork enclosures were no longer functioning as farmsteads or defended settlements, this particular rath became associated with outdoor Catholic worship. Mass rocks and informal gathering sites were scattered across Kerry and the wider country during the Penal era, when Catholic religious practice was suppressed under English law, and a substantial, sheltered earthwork would have made a practical and discreet setting for a congregation.

The structure itself is a univallate rath, meaning it has a single enclosing bank rather than the concentric rings seen at more elaborate sites. It is nearly circular, measuring 42 metres north to south and 41 metres east to west, which puts it comfortably within the range of a typical early medieval farming enclosure. The bank is well preserved, with a notably steep exterior face rising to 3.6 metres at its highest point, while the drop on the interior side is a more modest 1.6 metres. That asymmetry is fairly common in rath construction, the outer face being built up to present a more formidable appearance to anyone approaching from outside. A fosse, or defensive ditch, runs from the north around through the east to the south; it is shallow now, sitting roughly half a metre below the level of the surrounding ground and about 1.8 metres wide, with only slight traces remaining. The western side of the rath has been clipped by a later field boundary running north to south, a small intrusion that speaks to centuries of agricultural reorganisation layering itself over much older ground.

What makes Lissanaffrin quietly compelling is the double life implied by its name. The earthwork itself belongs to a pattern of settlement that was already ancient when the Normans arrived in Ireland. The association with clandestine worship came later, borrowing the physical presence of one era to serve the needs of another.