What exactly, nobody yet knows. The structure has spent the intervening centuries sealed beneath almost a metre of peat, and it only came to light because the bog itself began to give way.

In 2015, Dr Gill Plunkett identified the site after a section of bog at Calverstown collapsed, exposing worked timbers that had been preserved by the anaerobic, acidic conditions typical of Irish raised bogs. Peatlands are remarkable archives in this respect; the absence of oxygen slows decomposition dramatically, keeping organic material intact long after it would have rotted away in open ground. Plunkett retrieved some of the timbers and submitted one piece for radiocarbon dating. The result placed the wood firmly in the early medieval period, returning a calibrated date of AD 770 to 970. The timbers themselves include upright roundwoods around five centimetres in diameter as well as horizontal members, visible in a crevice that runs along the bog surface where it has partially slumped into a lower section of cutaway bog, the kind of industrially harvested terrain common across the Irish midlands. The verticals and horizontals sit roughly 0.8 metres below the original bog surface, and together they suggest a deliberate construction of some kind, though its purpose remains unresolved.

What makes the site particularly precarious is the same process that revealed it. The crevice created by the partial collapse continues to widen, and further slippage into the cutaway section below risks exposing and ultimately destroying the timbers entirely. A structure that survived the better part of a millennium undisturbed is now, through no particular drama, quietly running out of time.