The subterranean city holding half a million bodies and nine popes

Nature · Published 20 October 2026 · Updated 21 October 2026 Swipe more like this →

In short: Beneath the streets of Rome lies a sprawling labyrinth of five levels and twenty kilometers of passageways. This isn't just a cemetery; it is a monumental funerary complex that preserves the earliest sacred memories of Christianity, from the first public professions of resurrection to the tombs of early pontiffs.

The Catacomb of Callixtus, located on the Appian Way, is a massive underground complex spanning roughly 15 hectares. It is estimated to have held approximately 500,000 bodies at its peak. While it is often associated with the early Church, its development was a process of expansion. It is believed to have been created by Callixtus I, a deacon who enlarged pre-existing early Christian hypogea under the direction of Pope Zephyrinus.

The site is architecturally diverse, featuring grandiose underground structures such as the Liberian region and the region of Saint Gaius and Eusebius. It served as a primary burial site for the ecclesiastical hierarchy; the Crypt of the Popes alone contains the remains of nine pontiffs from the 2nd to 4th centuries. Notable inscriptions in Greek identify figures like Pontian, Anterus, Fabian, Lucius I, and Eutychian. It also houses the tomb of Pope Sixtus II, who was killed during the persecution of Valerian, and the grave of Saint Cecilia, whose relics were eventually moved in 821.

The catacomb serves as a chronological map of Christian theology. Early 2nd-century burials feature symbols like the Good Shepherd and fish (representing the Eucharist), while 3rd-century frescoes hint at baptism and the resurrection. By the 4th century, the site became so crowded that popes began being buried in other nearby catacombs, such as those of Priscilla and Balbina. The site remained largely hidden until its rediscovery in 1854 by the archaeologist Giovanni Battista de Rossi.

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