Entering in The catacombs of St.Callixtus there are two small basilicas with three apses, known as the "Trichorae". In the Easter one were perhaps laid to rest pope Zephyrinus and the young martyr of the Eucharist, St.Tarcisius.
The underground cemetery includes several areas. The Crypts of Lucina and the area of the Popes and of St.Cecilia are the most ancient areas (2nd c.). The other areas are named after St.Miltiades (half of the 3rd c.), St.Gaius and St.Eusebius (end of 3rd c.), the Western Area (first half of the 4th c.) and the Liberian Area (second half of 4th c.).