Eric and me left the car in a layby on the A487 right opposite the entrance to Castell Henllys.
We entered the field just yards from the car and made our way straight up hill, over one fence, and the henge/fort crowns the hilltop.
The entrances to the henge are at the northwest and southeast, I dont know if thats how most henges are, but it seems a point in favour to me.
The banks are almost covered with gorse and muddy as heck, making a circuit of the enclosure an endeavor in itself, but they are still tall, atleast 6ft in places.
If this hillfort was a henge then it was uncharacteristically large, especially so for south wales, there can't be many superhenges in the area, its not much smaller than the Mayburgh henge way up north.
Castell Mawr, a site just to the south of Castell Henllys in Pembrokeshire, has been considered an Iron Age hillfort for many years. However, in 1988 Harold Mytum and Chris Webster, archaeologists from the Universities of York and Southampton, published a report of their geophysical survey of the site. They concluded that Castell Mawr could be reinterpreted as a Late Neolithic/Early Bronze Age henge, which was later re-used in the Iron Age as an enclosed farmstead. The site is surrounded by Iron Age hill forts (Castell Henllys is only 1200m to the north) and is not particularly defensible. It has no external ditch, but a massive internal one between 10 and 15m wide and still up to 3m deep in places.