The Roman Catacombs, dating back to the 2nd century, are a vast network of underground burial sites extending over 600 kilometers beneath the city. Originally carved by the Etruscans for mining, they were later repurposed by Jewish and early Christian communities as cemeteries, as Roman laws banned burial within city walls. Christians favored burial over cremation, believing in bodily resurrection. These catacombs also served as secret meeting places during persecution, with frescoes and inscriptions revealing early Christian symbols. Notable sites like San Callisto and San Sebastiano house tombs of popes and martyrs. Today, five catacombs are open to the public, offering a glimpse into the spiritual and artistic legacy of early Christians.