I parked next to the reservoir entrance on the busy A478 as previously advised.
The Burial Chamber lies on the other side of the high hedgerow opposite. It was difficult to climb the hedgerow due to the steepness plus the brambles and nettles. Luckily I spotted a section of fence where the barbed wire was broken. Once I scrambled to the top I could immediately see the remains of the Burial Chamber just inside the field. There was another barbed wire fence on the other side of the bank which I was going to climb over but it was so rickety that I doubt I would have been able to get back over. With this is mind I settled for a view from the top of the bank – so close, yet so far.
There is a large capstone with several other stones sticking up out of the grass. There was an alignment of 3 larger stones. There were good views to the hills in the distance.
Carn Besi is a truly knackered burial chamber, and amidst all the other treasures on show in and around the Preseli's, there's probably not much reason to come here.
But and however, the site has a good panoramic view of the mountains, the capstone is I think intact, there may even be the last vestiges of passage stones directly infront of and leading to the chamber.
Plus it's so very close to the road and the parking is soooo convenient that I dont see how you wouldnt want to go have a look at Besi, plus it does have something else, something less tangible, something ethereal maybe, if you find out what it is let me know.
Visited 2nd March 2003: Carn Besi is situated right next to the A478 between Glandy Cross and Pentre Galar. There's a good parking space on the opposite side of the road to Carn Besi (by the entrance to the covered reservoir). Crossing the road is a bit tricky because it's quite busy. Then you have to scramble up the bank, avoiding brambles on the way. At the top watch out for the barbed wire. We managed to get our three year old son up there, but it was a bit of a struggle.
From this vantage point you can clearly see the capstone (this kind of thing) and some outlying stones between it and the fence. To get a better look you would have to hop the fence, but that would be both illegal and dangerous (because of the barbed wire).
This site is prominently placed, and based on a cursory look at the OS map may be aligned with Gors Fawr and Foel Feddau. It's a shame that so little remains of what must have been an important tomb.