In the back streets to the north of the village square lie Xerri's Grotto and Ninu's Cave . These fun underground caverns, complete with stalactites and stalagmites, are unusual in that they are both entered through private houses. Having discovered the caves beneath their homes, the owners decided to cash in on the tourist potential. Xerri's Grotto was discovered in 1923, and Ninu's in 1888. They're both fascinating and incongruous.
