Ah, my home county (albeit I grew up at the other end of it).
This is the stone circle, what's left of it:
https://www.themodernantiquarian.com/site/3452/penybeacon.html
In case you are bored and want some reading, here's a blog with a couple of stones around Dorstone (and Arthur's Stone):
https://www.themodernantiquarian.com/post/97342/stonespotting_in_southwest_herefordshire_around_dorstone_8_june_2011.html