Mysterious?

The Hellfire Caves (also known as the West Wycombe Caves) are a network of man-made chalk and flint caverns which extend 0.25 miles (400 m) underground. They are situated above the village of West Wycombe, at the southern edge of the Chiltern Hills near High Wycombe in Buckinghamshire, Southeast England.
They were excavated between 1748 and 1752 for Francis Dashwood, 11th Baron le Despencer (2nd Baronet), founder of the Dilettanti Society and co-founder of the Hellfire Club, whose meetings were held in the caves.[1] The caves have been operating as a tourist attraction since 1863.