Stone-lined, oblong, and sealed. Nobody alive has been inside them, and from the surface there is nothing whatsoever to see.

A souterrain is an underground structure, usually stone-built or earth-cut, associated with early medieval ringforts across Ireland. Their precise function is debated, but they were likely used for food storage, refuge, or both. The ones at Mylane appear to belong to a ringfort on whose northern side the hidden openings were once accessible from the interior. Writing in 1939, P. J. Hartnett noted, from local testimony, that these openings had previously led down into stone-lined chambers before being deliberately filled in. By the time anyone thought to record the fact formally, the entrances were already gone. Earlier still, around 1865, the Anglo-Irish soldier and ethnologist Augustus Henry Lane Fox, later known as Pitt-Rivers, had investigated souterrains in two ringforts in Mylane. He described earth-cut chambers with no stone lining, different in construction from the stone-lined rooms Hartnett later heard described. Whether Pitt-Rivers was working at this same ringfort or an entirely different one is something nobody has been able to establish with certainty. The two accounts sit in the record beside each other, connected only by location, and neither quite explains the other.

What makes the site quietly arresting is precisely this accumulation of partial knowledge. Pitt-Rivers dug and described; Hartnett collected memories of rooms already sealed; and the ground itself has since offered nothing further. The surface gives no indication of what may lie below it.