These are two giant standing stones, probably two of the tallest in Wales, standing thirteen feet and ten feet tall. They are situated in a field, and actually form part of the field boundary. The stones were recorded as being part of a stone circle the 17th Century, but the circle was allegedly demolished in 19th Century, by locals looking for buried treasure.
Specific Location: Llanfairpwllgwyngyll
There is much speculation over the age and use of Castell Bryn Gwyn (White Hill Castle). It was not a hillfort, being built on flat land, but excavations in 1959-1960 discovered that the rampart and ditch were similar to hillfort defences. It may have been a Neolithic henge monument, but nevertheless, there has been a long history of occupation at the site.