This impressive Neolithic burial site consists of two chambers and it was completely enclosed in a huge cairn measuring about 120 feet long by 50 feet wide. The smaller chamber is the earlier of the two and it is a fine example of the type known as portal dolmen. The larger tomb was built later, after which the two were enclosed together. When the site was excavated in 1960, broken pottery was found in the forecourts, and in the larger chamber were Bronze Age cremated human bones. The monument is signposted in Dyffryn Ardudwy village.