A ringfort, or rath, once stood here in pasture ground, a roughly circular earthen enclosure of around 40 metres in diameter, the kind of defended farmstead built across Ireland during the early medieval period, typically between the sixth and tenth centuries. It had two ramparts separated by a fosse, which is a defensive ditch, with a southeast-facing entrance some 24 feet wide. By the late 1970s, according to local information, it had been levelled. The land swallowed it.

What survives is a paper record that charts the site's slow disappearance. The Ordnance Survey six-inch map of 1842 shows a hachured circular enclosure, with the northeast side already truncated by a roadway. By 1904 the same map series records an external fosse running from the east-northeast to the north, suggesting the earthworks were still legible in the landscape if not entirely intact. The 1938 edition marks it as a raised area with an external fosse and an entrance to the southeast, still visible but diminished. Hartnett, writing in 1939, was able to record the two ramparts with their intermediate fosse and measure the entrance at 24 feet wide, meaning the site retained some structural coherence within living memory of its eventual destruction. The progression across those three map editions is a quiet record of attrition, each survey capturing a little less than the one before.

There is no earthwork to visit now, and the pasture at Rylane holds no obvious trace. But the sequence of maps documenting this particular rath offers a reminder of how much of the early medieval landscape persisted into the twentieth century before being cleared, and how routinely that clearance went unrecorded except in the gap between one survey and the next.