The great cavern of Tangrogo, near Abergele, Denbighshire, was formerly believed to be "enchanted" and to contain certain hidden treasures, guarded by a great dog of a supernatural species, kept there by the Three Fairy Sisters whose footprints were always to be seen in the mud of a small lodgement of water within the mouth of the cavern.
- Williams, J. (1860). The Records of Denbigh and its Lordship. Vol. 1. Wrexham : G. Bayley, p. 224.