A souterrain, for those unfamiliar with the term, is a stone-lined underground chamber or tunnel, typically associated with early medieval settlement in Ireland and often used for storage or refuge. What makes this one unusual is not its age or its construction, but the fact that it announced itself by accident, swallowed a portion of road, and was then promptly buried again.

According to local information, the ground collapsed during road works, opening a hole that revealed an underground passage beneath the carriageway. The collapse was filled in rather than investigated, and in time the road was resurfaced entirely. No trace remains at ground level. The site sits in south-east-sloping pasture with views toward Bantry Bay, which places it in a landscape that has seen continuous human activity since at least the early medieval period, when souterrains were commonly built across Munster. Whether this passage dates to that era, or belongs to some other tradition of underground construction, is simply not known; the opportunity to examine it properly came and went with the roadworks.

There is nothing to see at Knockroe today, and that is precisely what makes it worth knowing about. The site exists in the archaeological record as a probable souterrain, qualified by the word "possible" and supported only by the testimony of those who glimpsed it briefly before it disappeared. It is, in the most literal sense, a place that has been buried twice.