The south-west gable still stands within an oval-shaped graveyard on elevated grassland, and its 0.9-metre-thick walls preserve an unexpected amount of detail: a rectangular window opening roughly two and a half metres above ground, an offset on the internal face that once carried a wooden first-floor, and the curved voussoirs of an arch, the wedge-shaped stones that form its span, visible just below a twentieth-century memorial to the Mulligan family inserted into the wall. The base of the gable widens into an external batter, a deliberate outward slope at the foot of the wall, which may once have supported a belfry above the apex. The bulk of the church has vanished, probably dismantled by burial plots established after 1700.

The dedication is to St. Lonán, whose feast day falls on the 12th of November, and the site may overlie an early Christian monastery associated with him. By the medieval period it had become an established parish church in the diocese of Meath. In 1412, a priest named John Nugent was formally assigned to the parish following the death of one Henry Okelly, according to the Calendar of Papal Letters. Fifty years later, in 1462, Irish Chancery records describe a James Nugent as chaplain and rector of the church of St. Lonanus of Kilwelagh, placing the same surname in the parish across at least two generations.

Not everything from the medieval church has been absorbed into the graveyard soil. A single hammer-dressed jambstone from the original doorway, chamfered and finished with a bullnose stop, was repurposed as a capstone for the entrance stile to the graveyard, about 25 metres to the south-west. Just inside that gateway, the octagonal shaft of the medieval font and a bullaun stone, a boulder with one or more deliberately hollowed depressions that is typically associated with early Christian sites, sit together near the entrance. The surroundings are also worth noting: a tower house lies roughly 630 metres to the east, a motte castle about 320 metres to the south-south-west, and a stream runs 75 metres to the west, all within a landscape of poorly drained reclaimed ground that gives this cluster of monuments an air of long, layered occupation.