The book begins by detailing the architectural structure of the Catacombs, showing how they were excavated in the granular tufa specifically for Christian burial rather than being abandoned sand pits. It describes the narrow galleries, the tiers of loculi, the cubicula, and the multilevel piani, noting the precision required to secure maximum space with minimum excavation. The historical section traces the origin of the Catacombs back to Jewish burial customs and the early Christian rejection of pagan cremation. It outlines the periods of peace and the fierce persecutions under successive emperors from Nero to Diocletian, detailing the martyrdoms of bishops and confessors who sought refuge in these subterranean mazes.
The second part surveys the art, symbolism, and epigraphy of the Catacombs. The author analyzes the early Christian symbols, such as the good shepherd, the fish, the anchor, and the constantinian monogram, alongside the frescoes depicting biblical scenes from the Old and New Testaments. The final chapters discuss the inscriptions, examining how they reveal the daily life, character, ministry, rites, and doctrinal teachings of the primitive church, notably highlighting the immense contrast between primitive Christianity and later Romanism.
