When I was in England in the 80's, I went to Caerlon-on-Usk to visit Arthur Machen's homeland. It was as evocative as you might think, even though the ancient Roman bath is more of a tourist spot than a backward glimpse into history. You're on target with the Lovecraft reference--Machen was a major influence on the American writer. "The Terror" is another great Machen supernatural story (and was the uncredited source for Daphne duMaurier's and subsequently Hitchcock's "The Birds").

For a deeper understanding of what Wales meant to Machen, you may want to read his novel "The Hill of Dreams" and his autobiographical essays "Far Off Things" and "Things Near and Far" (available at Gutenberg I believe).

Thank you for publicizing this unjustly neglected masterpiece of horror.