At the southern foot of a small hillock in County Waterford, not far from the Brickey River, there is a site marked on the 1840 edition of the Ordnance Survey six-inch map with the plain, slightly solemn label: 'Tomb stone'. The name has stuck, though what exactly lies here is a little harder to pin down than that cartographic confidence might suggest. The site sits in the shadow of Knockmaon castle, and the designation on that early map is one of those moments where nineteenth-century surveyors recorded something they clearly found notable, without quite explaining why.

Separate from the tomb stone itself, a granite slab of considerable size, at least 2.25 metres long, 0.7 metres wide, and 0.25 metres thick, was once located roughly 40 metres north of a church in the same area. One face of the slab bears a raised ringed cross at its centre, the ringed cross being the form commonly associated with early medieval Irish Christianity, where a circle connects the arms of the cross. Its original function is uncertain, though it has been suggested it may have come from an altar. By the time Reverend P. Power was writing about the ancient ruined churches of County Waterford in 1898, and again when G. O'Connell-Redmond documented the castles of the region in 1918, the slab had already been moved from its original position to the tower house at Cappagh. A tower house, in Irish terms, is a type of late medieval fortified residence, a compact stone structure built for defence and status, and it was common for significant loose stonework to migrate to such landmarks over the centuries, whether for safekeeping or simply convenience.