• North Wales
  
• Bryn Celli Ddu
  Chambered Tomb

• ---

  South West Wales
• Carn Besi
  Chambered Tomb
• Cwm Garw
  Stone Pair
• Dolaumaen
  Standing Stone
• Gors Fawr
  Stone Circle
• Gors Fawr
  Stone Pair
• Rhos Fach
  Stone Pair
• Waun Lwyd
  Stone Pair

There are many megalithic sites in Wales but so far only eight have been surveyed as part of this archaeo­astro­nomical study. Like all the other surveyed sites (mostly Irish), they mark places where the shape of the horizon matches patterns in the sky.

The chambered tomb in North Wales, on the Isle of Anglesey, is an outlying example of the passage tombs that are common in Ireland and many other places along the Atlantic seaboard.

The remaining sites are almost all in North Pem­broke­shire, with one just over the border into Car­marthen­shire. These seven are a sig­nificant sample of the surviving prehistoric monuments that are situated on the south side of the Mynedd Preseli, around the headwaters of the Afon Cleddau.

The Preseli mountains are the reputed source of the bluestones that were transported to Stone Henge and erected there in prehistoric times. Down the River Cleddau to the sea at Milford Haven is the route by which they are most likely to have begun their journey. Indeed, one such stone was found on the sea-bed in that harbour.