Hidden behind the modest baroque facade is a sublimely simple 5th-century church. To the right of the altar stands a wooden effigy of St Antiochus, a martyr of North African origin who was enslaved by the Romans and later hid out in the basilica's creepy catacombs .
According to legend, Antiochus was condemned to work in the island's lead mines by the Romans after he refused to recant his faith. But he escaped, hidden in a tar barrel, and was taken in by an underground Christian group who hid him in the catacombs.
Accessible only by guided tour, the catacombs consist of a series of burial chambers, some dating back to Punic times, that were used by Christians between the 2nd and 7th centuries. The dead members of well-to-do families were stored in elaborate, frescoed family niches in the walls – a few fragments of fresco can still be seen – while middle-class corpses wound up in unadorned niches, and commoners' bodies were placed in ditches in the floor. A few skeletons lying in situ render the idea a little more vividly.
