According to legend, St 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 these catacombs beneath the Basilica di Sant'Antioco.
Accessible by guided tour, the catacombs consist of a series of burial chambers, some dating to Punic times, that the Christians used 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.