It is here, that according to Christian texts, St. Paul worked, preached and spoke with a group of sympathizers, hosted by Prisca and her husband Aquila. Several decades later, during the reign of Emperor Trajan (89-117) a rather large house with a nymphaeum was located here – its remains can be seen, going out of the nave on the right side of the church and arriving at the outer staircase leading into the underground. It is accessed, passing the remains of monumental granite columns, which were probably part of the Temple of Diana, which was located nearby in the past. A mithraeum was established in part of the ancient buildings at the end of the II century, which in 220 was widened with two side chapels. Despite the fact that the cult of Mithra was not officially accepted in the empire it was not persecuted either. It spread rapidly, especially in the II and III centuries of our era. One of the mithraea was found in the underground of the present-day church. This room, with a barrel vault was adorned with an image of the firmament with the signs of the zodiac marked upon it, which was connected with the cosmological ideas of this religion. The form of the Mithraic sanctuary itself, always relates to a cave, the place where the god Mithra was born out of a rock. That is why, these rooms are generally bereft of any light source and are illuminated solely with torches and olive lamps. The one here is in the shape of a quadrilateral and is finished off with an apse, in which there was an altar in the past. There is also a partially preserved relief depicting Mithra – a nude youth in a tunic, with a Phrygian hat on his head killing a bull – the pre-bull, the first being on the Earth, which was identified with the powers of darkness and evil. Mithra was sent by his divine father to save the world and was born on each 25th of December and died to once again be reborn. At the moment, when Mithra pierces the bull’s neck with a knife – in an act which is the crowning moment of his struggles – he is accompanied by a raven, dog, lion, and a snake, which drink the animal’s blood, as well as a scorpion which sucks its genitals. The symbolism of these animals is difficult to unequivocally interpret. The inscription on the wall proclaims – “ You have saved us, spilling eternal blood” – and it probably means that through the sacrifice of the bull, the forces of evil have been vanquished. There are also paintings on the walls: a procession of men in colorful robes and zoomorphic masks, which are to symbolize the seven grades of mystery. The procession is most likely a reference to the ceremony of initiation, which all those who desired to enter the circle of the initiated had to undergo. Some of the findings from this mithraeum are presently found in two different museums. The magnificent relief depicting Mithra is kept in the Museo Nazionale Romano alle Terme, while the partially preserved head of Helios (the sun-god) made of thin marble tiles (opus sectile) is at the Museo Nazionale Romano, Palazzo Massimo.

When in 392, Christianity became the official religion of Rome, places of pagan worship were successively destroyed, including those of the cult of Mithra, while buildings were handed over to the representatives of Christianity. Most often, on the destroyed ruins, churches for new heroes of the faith – martyrs – were created. And so it was with this very location. In 499, in church documents, this place is already referred to as tituli – titulus Aquila e Prisca. On the ashes of the mithraeum a church dedicated to St. Prisca was eventually erected, however the saint’s biography was altered. From the companion of St. Paul she became a legendary martyr, a virgin tortured by pagans. The remains of this church (the underground crypt) can be seen on the way to the mithraeum.

The crypt has the shape of the letter T, while its walls and the corridors leading inside, were decorated with frescoes in the XVII century. The altar is supposedly home the alleged relics of Prisca herself. We cannot be certain as to when the crypt was created, nor when the first early-Christian church was built here. The earliest mention of it comes from the year 777, when at the order of Pope Hadrian I, first church restoration was carried out. At that time a monastery was created here, designated for Greek monks who fled from Palestine (as was the case with the Church of San Saba). Later, it was inhabited by the Benedictines, who finally left this place after a fire in the XV century. The church was at that time severely damaged – three spans of the nave were destroyed, as a result of which in the middle of the same century, the building was shortened and rebuilt, during the pontificate of Pope Callixtus III. And despite the fact, that the pope offered it to the Franciscans, they, in fear of malaria – did not settle in it. Ultimately, it was given over to the Dominicans, who inhabited a nearby monastery at the Church of Santa Sabina – and they made their second residence inside. The next renovation was conducted in the year 1600 thanks to the financial support of Cardinal Benedetto Giustiniani. A courtyard was created out of the destroyed naves (left and main), while in the preserved right one, a sacristy was built. A simple, Mannerist, façade was erected, while the interior of the part above the arcades was decorated with frescoes depicting saints and angels holding the instruments of Christ’s Passion. The Mannerist frescoes – with scenes of Prisca’s martyrdom and burial – also appeared on the triumphal arch of the transept and walls of the presbytery. The painting in the altar, depicting the saint in a pose full of remorse and devotion, at the moment of her baptism at the hands of St. Peter – the work of Domenico Cresti (Il Passignano), also comes from that time.

Finally in 1660 the Dominicans were replaced by the Augustinians. The church interior, which threatened to collapse was once again restored in the XVIII century – the vault was replaced with a flat ceiling, the old columns with Doric capitols were built over.

One of the interesting objects found within is a baptismal font found on the left side, in which, according to Christian tradition St. Peter baptized Prisca. In truth these are the remains of an ancient column, which in the XIII century, was adapted for this function. Its opening is adorned with a contemporary sculpture depicting the baptism of Christ.