Dolwyddelan, Italy
Chwarel Ddu quarry was the earliest slate quarry in the Lledr Valley. It was working before 1810, and continued in sporadic operation until the late 1920s. It is about 0.5 miles (0.80 km) west of Dolwyddelan, just beneath Dolwyddelan Castle.
Listen to the audio guide for Chwarel Ddu Free on WIP — starts by itself when you arrive, even with the screen off