This ancient monument, now designated National Monument no. 139, sits on boggy grassland about 2.3 kilometres west of the bay, commanding impressive views towards the sea. The tomb’s elaborate structure consists of a coffin-shaped cairn measuring 46.3 metres long and up to 16.7 metres wide, bounded by drystone walling that was substantially restored by the Board of Works in the late 1880s.

The monument’s most striking feature is its large oval court, measuring 16 metres long and 12 metres wide, accessed through a short eastern passage. This court is defined by standing stones (orthostats) and gives access to four separate chambers; two subsidiary chambers open directly from the court arms near the entrance, whilst two parallel galleries at the western end are each divided into two chambers by stone jambs. Particularly intriguing are the picked motifs on two court orthostats beside the subsidiary chamber entrances, apparently prehistoric in origin and adding an element of ancient artistry to the structural grandeur.

The tomb’s restoration history reveals both gains and losses for archaeology. When Thomas Fagan first documented it in 1847, followed by Norman Moore in 1871, both found the monument difficult to interpret due to its disordered state. The Board of Works’ restoration, completed around 1887, involved clearing the chambers, removing cairn spill from the court, and rebuilding the drystone kerb based on what they found. However, T.N. Deane, the Superintendent at the time, mistakenly believed the structure was a cashel with cells rather than a chambered cairn, which may have influenced the restoration’s accuracy. Whilst this work preserved the monument for future generations and revealed its basic structure, it inevitably resulted in some archaeological information being lost, and questions remain about whether the restored cairn truly reflects its original prehistoric form.