Captivating Treak Cliff has a forest of stalactites and exposed seams of colourful Blue John stone, which is still mined to supply the jewellery trade. Tours lasting 40 minutes depart every half-hour and focus on the history of mining; kids can polish their own Blue John stone during school holidays. It's just under a mile west of Castleton's village centre.
Treak Cliff Cavern
Peak District