Until we reached it, I had no idea Rhaeadr y Cwm even existed (well done, tourist board...), but it's one of the most prominent waterfalls in Snowdonia, and hence the whole UK. The six-stage cascade falls ~120 m, the tallest section dropping 37 m.

Plaques at this viewpoint and the nearby car park state: 'For your enjoyment of this view: WRJ 1872-1954. The Rees Jeffreys Road Fund'. I thought they commemorated the construction of this precarious section of clifftop road, but I've since discovered the Fund is a national organisation. In addition to funding transport research and education, the Fund supports projects improving the roadside environment: it provided the viewpoint and car park.