Located about 170 metres northwest of what archaeologists call Site A, this ancient structure met an unfortunate end during the Victorian era. When road builders came through in the 1840s, they demolished the western half of what appears to have been a kerbed round mound, roughly 23 metres across, which contained some sort of internal structure. Local historian Thomas Fagan recorded that the construction work unearthed “many graves and human bones”, suggesting this was indeed an ancient burial site. The eastern half survived for another half century before being levelled around 1900, when more bones were reportedly discovered.

This lost monument was part of the larger Kilmonaster Passage Tomb cemetery complex, which continues to intrigue archaeologists. In 2005, archaeological testing was carried out just metres from one of the surviving passage tombs when a local farmer planned to build agricultural structures including a silage pit and cattle shed. The archaeologist, Richard Crumlish, dug three test trenches ranging from 16 to 36 metres long, finding mostly modern pottery sherds and a single worked flint in the topsoil. Some animal bones were discovered about 30 centimetres down, though the landowner explained these were from livestock burials in recent decades rather than ancient remains.

The site serves as a reminder of how much archaeological heritage has been lost to development over the centuries. While the original monument was destroyed before modern archaeological methods could properly study it, the discovery of human remains during both demolition phases, combined with its location within a known passage tomb cemetery, strongly suggests it was once an important prehistoric burial site. Today, nothing visible remains of this particular tomb, though the wider Kilmonaster complex continues to be protected and studied as part of Ireland’s remarkable megalithic heritage.