This area is littered with works of art made from rock which can only be viewed from the air. Check out this aerial from Google Maps to see what I mean.
In fact this may be the southernmost point of mainland Wales but the southernmost piece of land in Wales is the south-eastern tip of the island of Flat Holm in the Bristol Channel which is Lighthouse Point (ST 223646). Image at ST2264 : Flatholm island from m.v. Balmoral