Located on the eastern slopes of Mynydd Rhiw on the Llŷn Peninsula, this fascinating tomb incorporates two burial chambers. Originally covered by a large cairn some 35 metres (120 feet) long, it is believed that the tomb was originally constructed around 3500 BC in the style of a portal dolmen common to the area. This portal, capped by a huge slab, still survives today. Sometime around 3000 BC the tomb was modified to incorporate a long burial chamber in the Severn-Cotswold style.
Most monuments of this type are to be found in the area between Oxford and Bristol, though groupings also occur in Wiltshire and south Wales. The big question for archaeologists and historians is whether this represents the influx of a new people into this part of Gwynedd or is merely the introduction of new methods of tomb construction? It does suggest that extensive communication networks existed between the different communities of Neolithic Britain.
A third burial chamber once existed at the lower end of the cairn, but this is no longer visible today. The tomb lies in the grounds of the house of Tan y Muriau, about 400 meteres east of the church of St Aelrhiw.
Follow signs for Plas yn Rhiw (National Trust) off Mynytho to Aberdaron road B4413
Pwllheli - 11 miles
Plas yn Rhiw - ¼ mile or Rhiw Crossroads - ¾ mile
Regional Route 43 nearby
Walk up hilll from Plas yn Rhiw, turn right into Tan y Muriau and seek permission at farm.
Burial Chamber is on Private Land. Permission required from Tan y Muriau. Footpath nearby but monument is in field.
Full Figure Grid Reference: SH 238288 OS Landranger map sheet: 123