Pentre Ifan, a neolithic dolmen in Pembrokeshire, Wales UK

The dolmen dates from approximately 3, 500 B.C. and, possibly, was used as a communal burial. The existing stones form the portal and main chamber of the tomb, which would originally have been covered by a large mound of stones about 30 metres (98 ft) long and 17 m wide.[3] Some of the kerbstones, marking the edge of the mound have been identified during excavations. The stone chamber was at the southern end of the long mound, which stretched off to the north. Very little of the material that formed the mound remains.[3] Some of the stones have been scattered, but at least seven are in their original position. An elaborate entrance facade surrounding the portal, which may have been a later addition, [5] was built with carefully constructed dry stone walling. Individual burials are thought to have been made within the stone chamber, which would be re-used many times.[5] No trace of bones were found in the tomb, raising the possibility that they were subsequently transferred elsewhere.