The Cave of the Viper is a burial monument which was erected between the 1st and 2nd century AD. Lucius Cassius Philippus, a Roman who had been exiled to Sardinia, dedicated it to his wife Atilia Pomptilla, who was buried there. The legend tells us that during a bad illness that Lucius had been suffering from, his wife prayed so much that she ended up dying in his place. Though fairly small, the monument is important for the engraved poems in Latin and Ancient Greek at the sides of the grotto.