The buried popes: a tomb maze beneath Rome

The Catacomb(s) of Callixtus, one of the Catacombs of Rome on Via Appia Antica, lies beneath the city. It contains the Crypt of the Popes, which once contained the tombs of several popes from the 2nd to 4th centuries. Created by the future Pope Callixtus I, who was acting under Pope Zephyrinus, it expanded pre-existing early Christian hypogea. After a final wave of translations of relics from the crypt occurred under Pope Sergius II in the 9th century, primarily to San Silvestro in Capite, the catacomb was rediscovered in 1854 by the Italian archaeologist Giovanni Battista de Rossi.

Today the catacomb is part of a larger funerary complex known as the Complesso Callistiano, which occupies thirty hectares. The boundaries of this are taken as being the Via Appia Antica, the Via Ardeatina and the Vicolo delle Sette Chiese. The catacomb itself spans approximately fifteen hectares, descending for five levels. A rough estimate puts the length of passages at about twenty kilometers. The site contains the remains of around half a million bodies.

Sources: Wikipedia, OpenStreetMap, Wikidata, Wikimedia Commons