Sardinia was dominated by the Romans for almost seven centuries, from 258 B.C (after the Carthaginians' defeat) to 455 A.D (first Vandalic raids).  The city of Cagliari today still conserves relevant evidence of this history.
You can't miss visiting the "Viper's cave" (Grotta della Vipera), that takes its name from the two snakes engraved above the fa軋de.
The monument is situated in the neighbourhood of S. Avendrace, just at the entrance of the city if arriving from the main road n. 131.  Discovered in the 1822 while working on the Sardinia's main road "Carlo Felice" (road n. 131), it's a funeral monument hollowed out in the rock and dating back to the I Century A.D.  In ancient times, the surrounding area was employed for burials.
Originally, the grave's anterior was probably decorated with columns.  An inscription over the fa軋de indicates that it's dedicated to Attilia Pomptilla, a Roman matron.
The most interesting elements are the poetical inscriptions in Greek and Latin engraved on the internal walls of the cave.  They tell of the fond love story between Attilia and her husband Cassio Filippo.  He was a Roman noble who, during his exile in Sardinia, fell seriously ill.  Attilia, faithful wife, asked the Gods to let her die instead of her husband.  Her prayers were fulfilled and Filippo, in order to commemorate her, built this monument.
When he also died a little later, his ashes were conserved together with his wife's.