It has been levelled so thoroughly that it would be easy to walk straight across it without registering anything unusual. But look carefully at the ground and the shape of it becomes legible: a slightly convex interior roughly 65 metres across at its widest, edged by the ghost of a bank, a shallow ditch, and the remnant of a flattened outer bank beyond that.

This is a rath, the Irish term for a ringfort, the most common monument type in the Irish countryside. Ringforts were enclosed farmsteads, typically dating from the early medieval period, roughly the fifth to the twelfth centuries, and they were built by farming families to protect livestock and household from wolves and rivals alike. They were not forts in any military sense but rather the homesteads of a prosperous rural society, each enclosure defined by an earthen bank, a fosse (a surrounding ditch), and sometimes a second or even third outer bank. The Lisbunny example is a substantial one. Its interior diameter of 65 metres north to south and 59 metres east to west is well above average, and the presence of a fosse 7.2 metres wide and an outer bank nearly 9 metres wide suggests it was once a site of some consequence, even if centuries of agriculture have reduced those features to scarcely more than undulations. Field boundaries now cut across the northern and eastern edges, the ordinary geometry of later farming having overwritten the older one.