More commonly known simply as 'the Marble Church', completed and consecrated in 1860, this is a major landmark of the North Wales coast, visible from tens of miles away.
In researching these few details (I've passed it at least a hundred times in over thirty years, but only stopped once, a long time ago), I've found that a number of Canadian soldiers are buried here, having been shot for mutiny at a nearby army camp in 1918.
[It has been alleged that most actually died from illness, and that five were shot during the mutiny rather than being tried and executed afterwards; the distinction being that the former died without dishonour whilst the latter weren't officially found guilty of mutiny. I can't comment on this version's accuracy.]