The Grey Mare and her Colts
Long Bredy and Kingston Russell, United Kingdom
The Grey Mare and her Colts is a megalithic chambered long barrow located near Abbotsbury in Dorset, England. It was built during the Early and Middle Neolithic periods (3400-2400 BC). The tomb was partially excavated in the early nineteenth century, and was found to contain human bones and several pottery fragments.
Monument data from Wikidata (CC0). Summary from Wikipedia (CC BY-SA).