Excerpt from: Estelle Shohet Brettman, Vaults of Memory: The Roman Jewish Catacombs and their Context in the Ancient Mediterranean World, rev. ed. Amy K. Hirschfeld, Florence Wolsky, & Jessica Dello Russo. Boston: International Catacomb Society, 1991-2017 (rev. 2024).

The Christian catacombs of Rome were recorded in church annals and remained alive in tradition, but the Jewish catacombs seem to have been all but forgotten by the early Middle Ages, after they had ceased to be used as burial grounds. Since Bosio's discovery of a Jewish catacomb on the Monteverde in 1602, little ancient or medieval literary documentation of the Jewish cemeteries has been recovered, and hardly any useful epigraphic dates are available to researchers. Even so, scholars continue to put forth new theories about the dating of the Jewish catacombs. Among the few chronological indicators available from the sites themselves have been the markers' marks on the Roman bricks used in their construction. The marks give clues as to the dates when the bricks were produced, but cannot be relied upon to furnish exact dates for the tombs themselves, because the bricks could have been used or reused in this context long after their manufacture.[i]

It is difficult as well to establish firm dates based on inscriptions inside the catacombs because the styles of carving often persisted for considerable periods, and some inscriptions might not have been set in place until well after the earliest use of a catacomb.[ii] Thus, neither brick stamps nor epigraphy are considered chronologically definitive by today's scholars.

Other clues for dating have been sought in styles of construction and painted decoration, epigraphic names, coins, glassware and its workmanship, and the shape, design, color, and manufacture of the clay lamps found in the catacombs.[iii] Even so, it must be borne in mind that any chronology advanced for the catacombs based on material finds will be affected by accidents of discovery, the recycling of materials, the perpetuation of older styles and techniques, and progressive fragmentation and deterioration of the objects themselves, all of which can lead to distorted conclusions. As excavations beneath the topsoil continued in these sites, diggers inevitably encountered other burial chambers and broke through their walls. Entire burial sites might then be combined to expand a cemetery. A number of catacombs, such as the Jewish catacombs of Villa Torlonia, were designed from the beginning to be communal burial sites. That being said, the final extent of this site was only reached piecemeal, with additions to pre-existing galleries and the "break" in the floor of one level of galleries to permit access to others at a lower level.

[i] Brick stamps cannot serve as a "terminus ante quem non" since, as highlighted by L. V. Rutgers, the custom of imprinting stamps on bricks only commenced after the reign of Augustus (27 BCE-14 CE): L. V. Rutgers, The Jews in Late Ancient Rome: Evidence of Cultural Interaction in the Roman Diaspora (Leiden: Brill, 1995), p. 98.
[ii] Estelle Shohet Brettman wrote that she was "grateful to Prof. Mason Hammond of Harvard University for this information in a letter of September 8, 1982, as well as other assistance from him with difficult epigraphy".
[iii] N. Muller, "Il cimitero degli antichi Ebrei posto sulla via Portuense," in Atti della Pontificia Accademia Romana di Archeologia 12 (1915), pp. 244-248; U. M. Fasola, "Le due catacombe ebraiche di Villa Torlonia" in Rivista di Archeologia Cristiana 52 (1976), pp. 59-60.