now stands. It is possible that the inhabitants of the settlements near what is now Kilnaboy erected the structure to delimit the northern border of their territory, though it was also used for burials. Design Poulnabrone is the largest Irish portal tomb after Brownshill Dolmen in County Carlow. It is located on the remains of a mound, and consists of slab-like tabular capstone which is thirteen feet in length (around 4 metres), 2 metres (6 ft) to 3 metres (10 ft) wide and 30 cm (1 ft) thick. Unusually for dolmens of this type, the capstone slopes towards the west. The chamber's "roof" formed by this huge capstone is supported by two sets of slender upright parallel portal stones and orthostats (upright slabs), each about 2 metres (5 to 7 feet) high, which mark the entrance, and support the capstone from the ground, creating a chamber that tapers eastwards. Its cairn on average extends for 3 metres from the chamber. The upright stones stabilise the chamber and, as they are placed directly on the limestone bedrock, would have been no higher during the Neolithic period. The entrance faces north, and is crossed by a low sill stone, which is positioned on an east-west crevice. Three stones just before the sill stone form an antechamber backfilled with earth and stones. Radiocarbon dating indicates that the tomb was probably in use as a burial site between 3,800 and 3,200 BC. The findings are now at the Clare Museum, Ennis, loaned from the National Museum of Ireland. Excavations A spiral crack on the eastern portal stone was discovered by a local in 1985. As the crack was thought likely to destabilise the tomb, two phases of conservation were undertaken, both overseen by Dr. Ann Lynch, Senior Irish Government Archaeologist at the National Monuments Service. The dolmen was dismantled, and the cracked stone replaced during excavations in 1986 and 1988. Human remains The remains of around 33 people were found buried underneath the monument. All but one of the adults were under the age of 30. They lived between 3800 and 3200 BC, and can be assumed to have been members of a specific elite. In June 2020, the earliest incidence of Down syndrome was found in genomic evidence from an infant that was buried before 3200 BC under the monument. Personal items buried found along with them include a stone axe, jewelry made