This national monument is the Brownshill Portal Tomb located in Brownshill in co.Carlow. It is not only the largest example in Ireland but also in Europe with a capstone weighing in at an impressive 150 tonnes! Portal tombs are so called because the entrance to these burial chambers are marked by a pair of tall portal stones which are covered with a single capstone. The capstones usually rest and slope backwards. The earliest portal tombs date from 4000 b.c to 3000 b.c and many were surrounded by mounds of stones called cairns. These might have resembled a miniature ‘Newgrange’. Over time most of these stones have been removed for other purposes.