The Santa Costanza is a little gem. Located on the Via Nomentana, just a stone’s throw away from the Sant’Agnese fuori le Mura, it is not frequented much by tourists and I was in fact the only visitor when I visited the church in January 2017. The edifice used to be a mausoleum for Constantina and Helena, daughters of the Roman emperor Constantine the Great (306-337) and it was only converted into a church much, much later. The Santa Costanza is known for its colourful history and nice collection of Late Antique mosaics.
Constantine the Great’s family was large and extremely complicated. He was himself a child from his father Constantius Chlorus’ first marriage to Helena, the future Saint Helena (see Rome: Santa Croce in Gerusalemme). Chlorus later divorced her and married Theodora, who bore him six children. His firstborn was a boy named Dalmatius, who was thus Constantine’s half-brother. Dalmatius’ son Hannibalianus, ergo Constatine’s nephew, would marry Constantine’s daughter Constantina, a child from his second marriage to Fausta. When Constantine died in 337, a great purge took place within the imperial family and Hannibalianus was killed. Constantina subsequently remarried, this time to Gallus. Gallus was again a close relative, being another one of Constantine’s nephews. To be precise, he was the son of Julius Constantius, the late emperor’s half-brother (and brother to Dalmatius). So to sum up, Constantina twice married one of her own cousins.
The Santa Costanza was part of the large funerary basilica erected next to the tomb of Saint Agnes the martyr. It could be reached by entering the basilica and immediately turning left. Archaeological research has demonstrated that there was originally an older edifice on this spot, connected to the basilica and constructed at the same time. This seems to have been the original mausoleum of Constantina, who died in 354. For some reason the original triconch-shaped building was demolished and replaced with the present edifice. One theory is that this was done to create a splendid mausoleum for Constantine’s other daughter Helena, who died in 360. She was married to her cousin Julianus, who happened to be Julius Constantius’ second son (and brother to Gallus, Constantina’s second husband; I told you it was complicated…). Julianus became known as Julian the Apostate. He was sole emperor from 361 until 363 and previously served as Caesar and Augustus.
So we may accept that the Santa Costanza was originally a mausoleum built for Helena and Constantina, with the latter already interred in the predecessor of the mausoleum. This still does not explain the name ‘Santa Costanza’. Costanza would be Constantia in Latin, but that was actually the name of Constantine’s half-sister (the one who married his chief rival Licinius). Obviously daughter and half-sister were confused and it is not difficult to see why. A further problem is that neither was ever canonised, so technically there is no Santa Costanza among the saints recognised by the Roman Catholic Church. In fact, if we are to believe Ammianus Marcellinus, the actual Constantina was a horrible woman, a bloodthirsty harpy who had a bad influence on her husband Gallus. Even if his assessment is unfair, there is still no reason to honour her as a saint.
The mausoleum was not converted into a church until the pontificate of Pope Alexander IV (1254-1261). The two sarcophagi in the mausoleum, a larger and a smaller one, were later moved to other locations. It was originally believed that the larger of the two contained Constantina’s remains, but she may actually have been entombed in the smaller one, which is shaped like a bathtub. That would make the larger sarcophagus Helena’s final resting place. In any case, the larger sarcophagus was moved to the square in front of the San Marco church near the Capitol Hill by Pope Paulus II (1464-1471) and later to Vatican Museums in 1790, where it can be admired today. The sarcophagus that can nowadays be found in the Santa Costanza is a plaster copy, and a fairly convincing one.
The smaller sarcophagus was installed in the left transept of Saint Peter’s basilica in 1606. If the larger sarcophagus is indeed Helena’s, then it is her remains that Pope Alexander enshrined under the central altar. This is ironic for many reasons: not only was Helena never canonised (her grandmother was), the church is not even named after her and she was the wife of an emperor who became known for his anti-Christian policies!
In the seventeenth and eighteenth century, the church was a popular meeting place for a group of Dutch and Flemish artists known as the Bentvogels or Bentveugels. They called the Santa Costanza the “Temple of Bacchus” and assumed that the Greek god of wine had been buried in the larger sarcophagus (probably because of its Bacchic motifs and because of the mosaics in the mausoleum showing the grape harvest). To honour Bacchus, the Bentvogels held drinking parties and initiation rituals here which could easily take all night and day. Consecutive popes were not happy with these orgies, no doubt partly because of their pagan character (the artists made libations to Bacchus, which was markedly un-Christian). In 1720, Pope Clemens XI (1700-1721) ultimately suppressed the Bentvogels’ activities.
A closer look at the Santa Costanza
The Santa Costanza is a centrally planned, circular building, basically a ring within a ring. The central area of the church is surrounded by an ambulatory and covered by a dome which is some 19 metres high. The church somewhat resembles the Santo Stefano Rotondo on the Caelian Hill, but it is much smaller. In fact, it was never a parish church and nowadays mostly serves as a wedding location. When I visited the church, there were no other visitors, but the presence of cushions for bride and groom to kneel on made me suspect that either a wedding was planned later that day or this is a permanent feature of the Santa Costanza. Mass does not seem to be celebrated here.
When it was still a mausoleum, the building must have been entirely decorated with mosaics and marble revetment. It was unfortunately stripped of all of its marble in later centuries and most of the mosaics are gone too. The Portuguese artist Francisco de Holanda (1517-1585) was in Rome between 1538 and 1540 and visited the Santa Costanza. He made drawings of the ceiling of the dome, which show that the mosaics here were already in a deplorable state. Large chunks had fallen off. The dome mosaics were completely removed during interventions in 1620 and replaced with a very mediocre fresco in the eighteenth century, which had to be restored a century later. Looking at De Holanda’s drawings, one can only lament that the original mosaics never received proper maintenance. They must have been quite spectacular, with scenes from the Old and New Testament (here, here).
Fortunately, some of the mosaic decorations in the church have survived. We can find these mosaics on the ceiling and in two of the eleven niches of the ambulatory. The ceiling mosaics were made in the fourth century, so they can be dated to ca. 360. None of them are overtly Christian. We see geometrics patterns, but also birds (including peacocks), the grape harvest and wine pressing. These themes would have been acceptable to Christians and pagans alike.
The two mosaics in the niches were made later, perhaps between the fifth and seventh century. One of them shows a young, blond Christ with a blue halo flanked by Saints Paul and Peter. Peter is holding a scroll with the words DOMINVS PACEM DAT, “the Lord gives peace”. Also on the scroll is a chi-rho symbol. At Christ’s feet are four sheep. The other mosaic features an older Christ, seated on a globe. He again has a blue halo and his facial hair is a little unusual: he has a beard but no moustache. On the left we see Saint Peter, who is given the Keys of Heaven.
- Capitool Reisgidsen Rome, 2009 Dutch edition, p. 264;
- Henk Singor, Constantijn, p. 283-284;
- Luc Verhuyck, SPQR. Anekdotische reisgids voor Rome, p. 244-245;
- Santa Costanza on Churches of Rome Wiki.
 Daughter of the emperor Maximianus (286-305), sister of Constantine’s rival Maxentius and also sister (or half-sister) of Theodora, his own father’s second wife.