The cave was discovered in 1742 when workmen were building a bench for women selling butter and cheese in the Butter Market. As they banged a post into the ground, it nearly disappeared - by chance they had found the centre hole of a millstone which had been placed on top of the cave and covered over.
This was removed and the soil excavated, revealing carvings on the walls of crucifixion scenes and various religious figures, such as St Catherine, St Christopher, etc.
Most of the wall decoration is thought to have been done during the time of the Crusaders, when the cave was believed to have been used as a chapel by the Knights Templar organisation.
The entrance is beside the Cave Shop.