Outside the old Roman capital Mdina, we can find St Paul’s Catacombs, which is a typical complex of interconnected, underground Roman cemeteries, which were used until the 4th Century AD. St. Paul's Catacombs represent the earliest and largest archaeological evidence of Christianity in Malta and owes their name to the widely held myth that it was related to St Paul's Grotto. 

In the catacombs one can find a few surviving murals, these happen to be the only surviving evidence on the Maltese Islands of paintings from the late Roman and early medieval periods.

www.heritagemalta.org/museums-sites/st-pauls-catacombs