LOS ANGELES, CA (Catholic Online) - The burial custom of most ancient Romans tended to be cremation, with ashes stored in urns. Christian belief in the physical resurrection led the early Christians to bury their dead instead. Burial requires significantly more space and the early Christians did not own much land. The catacombs became a practical and necessary, solution for burial of the faithful.

In addition, the catacombs were an ideal way to strengthen the sense of Christian community and they provided quiet, out-of-the-way places for memorial ceremonies and displaying Christian symbols.

The first large-scale Christian catacombs were excavated in the 2nd century A.D.; all located outside the city walls as Roman law forbade burial within the city limits. The catacombs were also used for memorial services and celebrations of the anniversaries of Christian martyrs.

The catacombs have often been depicted as hiding places for Christian populations during times of persecution -- but there is little evidence for this. It probably only occurred in exceptional cases during the persecutions, when the catacombs were the only safe place to celebrate the Eucharist.

After Christianity became the religion of the Roman Empire in 381 A.D. and the cult of relics became an established part of Christian worship, the catacombs became a place of pilgrimage. Within centuries, the saints began to be buried in churches rather than catacombs and the faithful dead joined them in church cemeteries. By the 6th century catacombs were used only for martyrs' memorial services. The Ostrogoths, Vandals and Lombards that sacked Rome also violated the catacombs, taking whatever valuables they could find.

By the 10th century the catacombs were mostly abandoned and they remained forgotten until their discovery in 1578. Antonio Bosio spent decades exploring and researching them for his Roma Sotterranea (1632) and, two centuries later, the archeologist Giovanni Battista de Rossi (1822-1894) published the first extensive professional studies about catacombs. In 1956 and 1959 more catacombs were discovered near Rome.

Some of the catacombs are open to the public and they are one of the most popular stops in Rome for tourists and pilgrims alike.