That alone is unusual enough, but what gives the place a stranger quality is where tradition says the tunnel led, and why.

A souterrain is an underground stone-lined passage, typically associated with early medieval settlement in Ireland, used variously for storage, refuge, or concealment. When investigators opened and explored this one in the 1940s, they followed it for some 400 yards. Local tradition, recorded by McCarthy in 1977, holds that the passage was used by the monks of Kilnamanagh Church, which sits roughly 90 metres to the south-east of the churchyard where the souterrain begins. The name Kilnamanagh itself, from the Irish Cill na Manach, means church of the monks, which lends some weight to the association, even if the mechanics of the connection remain unclear. Whether the passage was a practical route between ecclesiastical sites, a means of escape during periods of instability, or something else entirely, the record does not say with certainty. What remains is the detail of a tunnel measured, walked, and then largely left to its own quiet existence beneath the field.