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Underground secrets of St. John in Lateran

This post is also available in: Polish (polski)

Underground of St. John in Lateran
Underground secrets of St. John in Lateran

Monumental St. John in Lateran is probably known to everyone who has been to Rome. But the magnificent structure hides in its basement many ancient secrets that have so far been only partially known. The history of this place is really fascinating – it dates back to the struggle for the domination of Christianity in the Roman world and civil wars for imperial power.

We find there traces of a conspiracy against the emperor, a brotherly conflict that ended with the murder of one of the siblings and the everyday life of the Romans. A few months ago, I had the opportunity to visit the underground, and entering them was like a journey through time. Going down there, I experienced a great surprise – although at first, I felt a slight disappointment with the basement and “not very ancient” character of this object, with each step I discovered something new and surprising. Finally, I decided that this was one of the biggest surprises that awaited me during my last stay in Rome.

I will start today’s story from the end, going back deeper and deeper into the past. I make a reservation in advance: I was not guided by a professional guide, so after returning, I had to gather information about the history of these areas before building the Basilica of St. John. Unfortunately, the ruins of buildings under the church have not been the subject of much research, so there is little research on them. Most sources only provide general data, and moreover – often contradictory data. Therefore, if you come across some information on the web that differs from what I present below – do not be surprised. I myself had to choose between different interpretations of the archaeological data. But to the point…

We remember first of all from history that the Lateran basilica and the adjacent papal palace were always places of particular importance to the Church: that the oldest basilica was founded there by the first Christian Emperor Constantine the Great and that before the Vatican became the seat of the popes, the official head of the Church was precisely in the Lateran. Why exactly there? What made the Lateran Church as important as the Vatican, which was, after all – sanctified by the martyrdom of the first Christians and the presence of the tomb of St. Peter?

The excavations at St. John in Lateran was confirmed by earlier information provided by ancient chroniclers. It was no accident that Constantine the Great chose this location for his basilica, as it was highly symbolic. For over a hundred years before Constantine, this place was the barracks of the elite imperial guard – equites singulares Augusti. Immediately after Constantine defeated his rival Maxentius in the Battle of Mulvian Bridge and triumphantly entered Rome, he ordered the guard barracks (the so-called Castra Nova) to be demolished and ordered a basilica to be built there. The Guard itself was disbanded. What did the guards like about the emperor? Well, in the fight between Maxentius and Constantine, they sided with the former. The dissolution of the guard, the demolition of its barracks and the foundation of a church in their place are, therefore, a symbolic act, on several levels: – it is an expression of the new emperor’s triumph over Maxentius – it is an act of gratitude for divine help in defeating the enemy, – it is a clear demonstration of a new opening in relations of power with more and more followers of the new religion. And finally, the most important thing: it is emphasizing that while Maxentius based his authority on the strength of the army, the new ruler builds it on relations with the Church. This alliance between the throne and the altar will survive the fall of the empire – both in the West and in the East, but that’s a topic for another story…

In the basement of the Lateran Basilica, you can find the oldest apse of the Basilica of Constantine, as well as the ruins of the guards’ barracks. In the tangle of foundations and walls from different eras, it is not easy to find your way around, but fragments of vaulted rooms in which the soldiers of the Emperor’s protection stayed are clearly visible here and there.

While visiting the basilica’s underground, you can see only a small fragment of the barracks. The whole area was about two and a half hectares in the area now fully occupied by the basilica, the papal palace and part of the square in front of them, so it was a huge area.

The most interesting of the barracks are small fragments of the walls of the headquarters of the guard commander. Unfortunately, there are not many of them left. To see their remains, you have to tilt your head – fragments of walls painted red and with white patterns can be seen high up under the ceiling. It is a narrow strip of walls, the so-called praetorium – the headquarters of the commander, which was exactly in the middle of the barracks. When you are in the nave of St. John, closer to the entrance, you are standing directly above the house of the imperial elite guard commander.

However, it is not the barracks that attract the greatest attention, but what was in this place before it was built. It turns out that the walls of the military praetorium were built largely on the walls of the older patrician domus. It is located directly under the praetorium. Almost complete rooms with beautiful black and white mosaics, elegant frescoes in cream tones and delicate patterns have been preserved.

The ruins of the second patrician house are located under the floor of the nave of the basilica closer to the transept. It is not entirely clear to me when this house was built. In the studies, I found information that it is slightly younger than the first, but I am not sure about this – the beautiful frescoes refer to the so-called fourth Pompeian style and bring to mind painted decorations on the walls of Roman houses from the 1st century CE Only small fragments of this residence have survived, making it impossible to recreate the whole. However, it had to be very impressive – what we see today is primarily a piece of a long corridor which – referring to contemporary buildings – cuts the basilica under the ground diagonally at the level of the transept. The orientation of the corridor (as I mentioned – diagonal to the basilica) suggests that the house must have been adjacent to the ancient Via Tuscolana, running slightly more to the west. Interestingly, the nearby St. John – if you don’t believe me, take a look at Google Maps! Exactly! Well, this baptistery is so old that its location is a kind of memento of the location of all the houses that stood nearby – in this house under today’s basilica!

Both houses were destroyed and the barracks for equites singulari Augusti were built on top of their rubble. I found information about their destruction in the earthquake, but it seems a bit suspicious to me. In the second of the discussed houses, it is clear that all marble cladding has been carefully removed from the walls, which suggests a methodical dismantling of the most valuable elements of its equipment. It is rather difficult to imagine such actions in the event of an earthquake – if it were so strong that it would result in leaving the house, most of the stone cladding would probably be significantly damaged and no one would bother with them. So I would assume that the land where the house was located was simply used for other purposes and that both residences were partially demolished, partially filled up.

Who did the patrician houses in question belong to? It’s hard to say, but some associate one of them with Gnaeus Calpurnius Piso. It would be absolutely fascinating if it turned out to be true. Why? Because Pizo is a colourful person of the 1st century CE – remember Caligula taking Orestylla from the altar and raping her almost in front of her would-be husband? This would-be husband was precisely Gnaeus Calpurnius Piso. A quarter of a century later, the same Piso was also involved in a conspiracy against Nero. Then the house of Piso was confiscated by Nero and entered the imperial domain. According to legend, two hundred and fifty years later Faustina, wife of Emperor Constantine, was to live in one of these houses.

There is a little curiosity between the two houses – a bread oven, similar to the ones you can see in, for example, Pompeii. Was it related in some way to any of the houses? What period exactly does it come from? Unfortunately, I do not know.

Another interesting fact is the Ionian capital found in the ruins. It is interesting because its left part lists members of the imperial Septimius Severus. There is a place after the “rubberized” Geta – murdered by his brother Caracalla: a memento of a brotherly conflict, as a result of which Geta was to be condemned to eternal oblivion.

But the treasures are not over! Under a part of the basilica (right next to St. John’s Baptistery), there are also the remains of the former baths. It is not entirely clear whether these were public or private baths. Their history is quite complex – I read that they were built during the time of Hadrian or Antoninus Pius and that they had been badly damaged during some earthquake during the Severus dynasty. They were rebuilt by Septimius Severus or by Caracalla. Since they are practically adjacent to the Baptistery of St. John, which is an older Roman building adapted for sacred purposes, it is possible that the baptistery is somehow historically connected with the baths mentioned above. Perhaps they were arranged in which of the thermal rooms?

Author: Michał Kubicz - sekrety Rzymu (translated from Polish: Jakub Jasiński)

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