“Whatever was [the mound on top’s] primary destination, I am informed by Mr. Owen, that, according to a tradition in the neighbourhood, and particularly among the present race of bards, it was once a celebrated place for holding the Eisteddfod, or bardic meetings.
Twyn Barlwm, being situated on the highest point of the chain which bounds the rich valleys watered by the Usk, commands one of the most singular and glorious prospects which I had yet enjoyed in Monmouthshire; and which cannot be reduced to a specific and adequate description..
He does go on to try though. This is from William Coxe’s Historical Tour in Monmouthshire (1801).