Rhiwbryfdir, Italy
Oakeley quarry is a slate quarry in the town of Blaenau Ffestiniog, north Wales. It was the largest underground slate mine in the world, and had 26 floors spanning a vertical height of nearly 1,500 feet (460 m).
Listen to the audio guide for Oakeley Quarry Free on WIP — starts by itself when you arrive, even with the screen off