sentences:  When the catacombs were first explored by archaeologists in the 20th-century, the tombs had already fallen into great disrepair and neglect, and the sarcophagi contained therein had almost all been broken-into by grave-robbers in search for treasure.This pillaging was believed to have happened in the 8th and 9th centuries CE based on the type of terra-cotta lamps found "in situ".The robbers also emptied the stone coffins of the bones of the deceased.