It was discovered by local resident Anthony Xerri in 1923[1] or 1924[2] while digging a well under a private house.

Xerri's Grotto is not far from another underground feature, Ninu's Cave, which was discovered in 1888 in a similar fashion, when a well was being dug under a private house.

It contains various calcified formations, including stalactites and stalagmites, some of which resemble a tortoise, a vulture, giraffes or elephant's ears.

The cave was extended during World War II, when the family used it as an air raid shelter.

[2] Today, the cave is illuminated by electric lights, and is open to the public with tours being given by the owners of the house.