During a period of persecution in the 3rd century, early Christians buried their dead in the Catacombs of St. Callixtus
There are 90 acres of cemetery space and 12 miles of galleries in the St. Callixtus Catacombs - some of the biggest in Rome
Half a million Christians, martyrs, as well as 16 popes are buried in the underground cemetery
The ancient crypts contain Greek inscriptions and symbols carved into the stones
The Area of the Popes is the most venerated crypt, dubbed ‘the little Vatican’ as it is the resting place of nine popes and eight Church dignitaries