The Catacomb(s) of Callixtus is one of the Catacombs of Rome on the Appian Way, most notable for containing the Crypt of the Popes, which once contained the tombs of several popes from the 2nd to 4th centuries.
The Catacomb is believed to have been created by future Pope Callixtus I, then a deacon of Rome, under the direction of Pope Zephyrinus, enlarging pre-existing early Christian hypogea. Callixtus himself was entombed in the Catacomb of Calepodius on the Aurelian Way. The crypt fell into disuse and decay as the relics it contained were translated from the catacombs to the various churches of Rome; the final wave of translations from the crypt occurred under Pope Sergius II in the 9th century, primarily to San Silvestro in Capite, which unlike the Catacomb was within the Aurelian Walls. The Catacomb and Crypt were rediscovered in 1854.
The underground cemetery includes several areas. The area of the Popes is the most important and venerated crypt of the cemetery, called 'the little Vatican' as it was the official burial place of nine popes and, probably, of eight dignitaries of Rome's 3rd century Church. In the walls you can still see the original inscriptions, in Greek, of five popes. On four tombstones, near the name of the pope, there is the title of 'bishop', since the Pope was regarded as the head of the Church of Rome, and on two of them there is the Greek abbreviation of MPT for 'Martyr'.
Passing through imposing galleries full of loculi, we reach five small chambers, truly family tombs, commonly known as the cubicles of the Sacraments, and particularly important for their frescoes.
References:The Gravensteen is a castle in Ghent originating from the Middle Ages. The name means 'castle of the counts' in Dutch. Arnulf I (918–965), Count of Flanders, was the first to fortify this place, building a medieval bastion on this high sand dune, naturally protected by the river Leie and its marshy banks. This bastion consisted of a central wooden building and several surrounding buildings, also in wood.
In the early 11th century, the wooden building was replaced by a stone residence, consisting of three large halls that made up three storeys, connected by a stone stairwell. The monumental stone staircase, the light openings, the fireplaces built into the walls and the latrines were signs of considerable luxury and comfort in those days. There was probably also a tower.