After the Quo vadis church, to the right of the Appia Antica, are the Catacombs of St. Callistus, among the largest and most important in Rome. They date back to around the middle of the 2nd century and are part of a cemetery complex occupying an area of 15 hectares, with a network of tunnels almost 20 kilometres long, on different levels, and reaching a depth of more than 20 meters. Dozens of martyrs, 16 pontiffs and many Christians were buried there.
They are named after the deacon St Callistus, who, in the early 3rd century, was appointed by Pope Zephyrinus to administer the cemetery. The Catacombs of St Callistus became the official cemetery of the Church of Rome. Two small basilicas with three apses, known as ‘Tricoras’, are visible above ground. Pope St Zephyrinus and the young martyr of the Eucharist, St Tarcisius, were probably buried in the eastern one.
The underground cemetery consists of several areas. The Crypt of the Popes is the most sacred and important place in these catacombs. It is also called ‘the little Vatican’ because nine popes and probably eight dignitaries of the 3rd century Church were buried there. Along the walls are engraved the original inscriptions in Greek of five popes. On four tombstones, next to the name of the pontiff is the title ‘bishop’, a reference to the pope as head of the Church of Rome, and on two tombstones there is also the Greek abbreviation ‘MPT’ for martyr.