The Crypt of Pope St. Gaius
The Crypt of St. Gaius has a special place in this cemetery, because of its exceptional proportions. It can hold more than 60 persons! From the beginning, it was designed on this scale to provide for the community assemblies. By means of the ample light-shaft in Gallery Q1, the crypt was well lit and sufficiently ventilated. The decorations are sober: the walls were covered with a single layer of white stucco.
There are many tombs on the side walls of the crypt; on the end wall there are only three. The tomb in the middle stands out because of its size. It is the most important in the whole crypt and contains the fragments of the Greek inscription of Pope St.Gaius: "Burial of Gaius, bishop, April 22nd" (of the year 296).
We also find in the crypt some Greek and Latin inscriptions, unfortunately almost all made up of fragments, and some graffiti like these: "O Lord , help your servant Benjamin" and " The spirit of Silvanus. In peace". Also the floor of the crypt is filled with tombs. On the walls of the Crypt of St. Gaius the graffiti indicate the names of three African bishops, who had come to pray at the tomb of their fellow countryman St. Optatus, probably buried in this crypt.

The Crypt of St. Eusebius
This crypt is in front of that of St. Gaius. It is rectangular and not very spacious. The walls of the crypt and the floor were decorated with marble. A modern light-shaft now opens where the roof had partly collapsed. The original light-shaft was located in the ceiling of Gallery Q1, also shared by the Crypt of St. Gaius.
The crypt contains three arcosolia. St. Eusebius was laid to rest in the arcosolium located in the right wall of the crypt. The arches of the arcosolia were embellished with mosaics. Inside the arcosolium there is a large modern marble-slab, which contains the original fragments of the inscription written by pope Damasus in honour of St.Eusebius.
On the centre of this burial chamber we find a monumental marble-slab engraved on both sides: on one side it bears a rough copy of the inscription by Pope Damasus; on the other side there is an inscription in honour of emperor Caracalla.

The inscription of Pope Damasus recalls the goodness and mercy of Pope Eusebius towards the lapsi, that is, those Christians who in order to avoid martyrdom or other forms of persecutions had renounced their faith. Once the persecutions ended, the greater part of those apostates asked to be readmitted to the Church community. These requests were opposed by the rigorists who were against granting pardon. They were headed by Heraclius, a representative of the Roman Clergy.
On the contrary Pope Eusebius taught that, following the example of Christ, Who had always forgiven sinners, the lapsi, after an adequate period of penance, were to be pardoned This problem had been much debated at the time of Pope Cornelius (251-253) and at the beginning of the 4th century. As the situation worsened to the point of disturbing public order, emperor Maxentius banished the religious leaders of both the opposing factions.
Pope Eusebius was forced into exile in Sicily, where he died shortly afterwards out of starvation. The Church quickly considered him a martyr. When calm was restored in Rome, Eusebius' body was translated by his successor St. Miltiades, and buried in the Catacombs of St. Callixtus, in the crypt which was named after him.
The poem bears the dedication "Bishop Damasus composed (this inscription) to honour Eusebius, bishop and martyr". Here is the text of the poem:
 

The Crypt of the Martyrs SS. Calocerus and Parthenius
Leaving the Crypt of Saint Eusebius and beyond a crossing of galleries, there is on the left the Crypt of SS.Calocerus and Parthenius, two martyrs who were perhaps victims of Diocletian's persecution in 304.
Next to the entrance door, on the left wall, there is a graffito written in Latin:

The burial chamber has been completely restored in late antiquity to prevent the collapse of friable tufa. The crypt excavated opposite that of Calocerus and Parthenius is of considerable proportions and was used as a place for worship next to the venerated tombs.
Following the route along Gallery Q1, there is a double cubicle which in ancient times was illuminated by a wide light-shaft. On the left is the cubicle of the 5 Saints.

The cubicle of the 5 Saints
This cubicle was so named because on the front wall five persons "Oranti" in a garden are painted. The scene, graced by the song of birds, and with trees laden with flowers and fruit, is a clear image of paradise, the blessed land reached by the fortunate souls. The names, with the well-wishing "in peace", are written over each figure: "Dionisia in pace, Nemesius in pace, Procopius in pace, Eliodora in pace, Zoe in pace".The whole picture dates back to the beginning of the 4th C.
Opposite the cubicle of the 5 Saints is the cubicle of deacon Severus.

The cubicle of deacon Severus
The double cubicle belonged to deacon Severus, who was authorized to excavate it by pope Marcellinus (296-304). Inscribed on a marble screen ("transenna") which closed an arcosolium, there is a long inscription in verse, which is one of the most important and evocative of subterrenean Rome.
The first lines of the inscription speak about the ownership of the cubicle:
"This deacon Severus, authorized by his PP (pope) Marcellinus, made a double cubicle with arcosolia and the light shaft, a quiet and peaceful resting place for himself and his own, to keep for a long time those beloved members sleeping and waiting for God, their creator and judge...".

In his inscription, Severus goes on with the affectionate recollection of his little daughter: "Severa, sweet to her parents and to her servants, gave up her innocent soul on the 25th January. It pleased God to grant her marvellous wisdom and beauty from birth ...".
The inscription of Severus is important from a dogmatic point of view, for the reference to the resurrection of the body: "The mortal body is buried here until He (the Lord) makes it rise again. And the Lord who has taken (from Severa) her chaste, pure and forever inviolable soul with her saintly spirit, will give it back adorned with spiritual glory. She lived nine years, eleven months and fifteen days. Thus she passed from this earthly life".
The inscription is also important historically, because it is the first inscription in which the bishop of Rome is given the title of "pope"(father). Since then the term was used as a synonym for the bishop of Rome. In the transenna the word is not carved fully, but with the sign "PP". It may be noted that this abbreviation is still used by the popes for their signatures.
Proceeding through Gallery Q1 and turning to the left, Gallery R2 is reached, with the pleasant surprise of the so-called "Cubicle of the Sheep".

The cubicle of the Sheep
The cubicle was excavated in the front wall with a large niche for a sarcophagus. It was decorated with frescoes in the mid-4th century, and it was badly damaged by the opening of one loculus. At the centre of the arcosolium is the image of the Good Shepherd with a lamb on his shoulders, surrounded by a ram and a few other sheep. The sheep is a clear symbol of the soul who, saved by Christ, now lives happily in paradise. Two men, one on each side of the picture, move eagerly to drink at the two springs which gush from the rock: they are two of the blessed, refreshing themselves at the fountains of the living water, Christ.
On the left wall of the niche we find a scene uncommon to frescoes, though frequently represented in sculpture: Jesus lays his hands, as a gesture of benediction, on the loaves and fishes presented by two apostles. On the ground are six baskets of loaves, each loaf marked with a cross. The fresco was subsequently damaged by the digging of a small niche for oil lamps.
On the right wall of the arcosolium is represented Moses in the act of taking off his shoes. In the very next scene Peter strikes the rock in order to get water from it. A soldier, sword at his side, takes the water in his hand to quench his thirst.This soldier, as portrayed by the painter, is not Hebrew but Roman, easily recognizable from his uniform and weapons. Moreover, the features of Moses, who is striking the rock, are very similar to those of the apostle Peter. Moses is symbol of the ancient law, Peter of the new one. The soldier represents the first pagans converted by Peter.