Pula Cathedral is a Roman Catholic church that stands on a site of the much older historic church. It is hard to say when first Christian communities appeared in Pula. For the first three centuries Christians were hunted and killed by the Roman officials. The first Pula Cathedral was erected on this spot in the 4th century AD. It was a site for worship, celebration and in time of danger last refuge. After Christianity became a legal religion in Roman Empire (Edict of Milan - 313 AD) Pula Christians created a large place of worship. After a devastating fire of 1242 Pula Cathedral was reconstructed. Although the roof and parts of the church were fixed, the base was kept pretty much untouched. Fragments of mosaics dating to 5th and 6th centuries AD are still visible today. Additionally Pula Cathedral keeps a Roman sarcophagus that dates back to the 3rd century AD. Apparently it houses the remains of the unknown Christian martyr that was killed during one of the waves of Christian persecutions. The bell tower of the cathedral was constructed in the 17th century from stones that were quarried at the Pula amphitheater.