Basilica di San Clemente: the most interesting historical site in Rome

By choosing to look – and eventually dig – down, we unearth the most important footsteps in the city’s timeline. Indeed the Renaissance itself was to a large extent ushered into existence by the commitment of a handful of enlightened individuals to make a more concerted effort to observe and copy what was occasionally revealed hiding in the ground beneath their feet; to look in depth at what the passing centuries had concealed, and to try to imagine what it had once been.

What these early archaeologists discovered was breath-taking. Every sculpture, every hidden building revealed a past so glorious that it had to be seen to be believed. Their curiosity of spirit has profoundly affected the ways in which Italians have interacted with their past ever since.

Today, more than 500 years after excavations started in earnest, the process of unveiling the many layers of Rome has really only just begun, and will never end. Every year thousands of new discoveries are made; each time the city authorities try to lay a new pipeline or upgrade the Metro system, substantial relics of the city’s past are exhumed from their earthen graves, forcing workers to down tools for months, or even years. It is no exaggeration to say that there are entire cities still lying below modern Rome, each one a single stratum of an ever-expanding geological puzzle.

It is in the Basilica of San Clemente, in a quiet backstreet not far from the Colosseum, where this unexpected journey through the sediment of history is perhaps most clearly and fully revealed. 

The church that today stands at ground level of the city could hardly be considered modern: it was completed at the beginning of the 12th century, and its cloistered courtyard and magnificently preserved gold-leaf mosaics within provide a jaw-dropping reminder of the skills of medieval artists. But walking into the cool, dark, 900-year-old church is only the beginning of our descent into the past here. 

The inspiration to investigate what lies beneath was that of one Father Joseph Mullooly of Rathcline, County Longford, Ireland. San Clemente has been managed under the auspices of Dominican friars from Ireland since the late 17th century, a responsibility granted by their Roman brethren as they escaped persecution by British forces in their home country. 

In 1857, as the de facto prior of the basilica, Father Mullooly discovered the top of a much older church embedded in the foundations of the current basilica. Inspired by the latest in archaeological research – in those days the cutting edge was published in the English language, thus putting the Irish friars a few steps ahead of their Italian counterparts – he began to excavate the crypt.

What was revealed, after years of setbacks – including occupation by Garibaldi’s army, hostile to the church – was astonishing: buried beneath the medieval basilica is another, far earlier church; an important one, which dates back to at least the 4th century AD. And beneath that lies something even more fascinating.

In the early Christian period in Rome, when the time came to create a new church for their congregation, rather than move to a new site or destroy a beautiful-but-outdated building, the elders would simply build on top of it, buried as many structures were by silt from the Tiber’s annual floods; or they would use its structure as foundations for the new building – and thus at San Clemente they inadvertently preserved at full height the older church’s murals, treasures, and ossuaries, even while forgetting about their existence.

On the walls of the underground church are significant frescoes, one of which carries one of the earliest examples of written Italian, and in here is buried Saint Cyril, the man who brought Christianity to the Balkans, and who gave his name to Cyrillic, the script he devised. Now fully excavated, we can be thankful for the original church-builders’ inadvertent foresight, an example of accidental conservationism-through-abandonment from nearly a millennium ago.

But the time travel doesn’t end here. Descending again, beneath this church-under-a-church, there is an even steeper staircase, and in yet another layer of time you are transported into the first century AD, to the streets of pagan ancient Rome, and the earliest years of two small religious cults.

This was a time when to practice unofficial religions was still a criminal offence, sometimes harshly punished by Roman law. Down an alleyway we find ourselves passing the wall of a large building, the dormitory of gladiators, and a private house with a courtyard, in all likelihood owned by one of the religions’ early converts.

Facing each other across the alley are the remains of two temples where obscure new religions could be practiced in private: Mithraism and Christianity.

Christians could practice their faith in their small room, hidden away from those passing by along the adjoining alleyway. And adjacent to this, another minority religious community had a cellar-like space in which banks of stone seating lined the room, surrounding an altar adorned with the cult’s most important image: that of the god Mithras slaughtering a bull.

The world of these ancient cults seems to be only very tangentially linked to our own, but it is in fact in these contested spaces that our modern world began to take shape: it could have been Mithraism that ‘won’ the battle of the cults, and whatever form a large public Mithraic temple may have taken could now be standing at street level. 

In reality Mithraism disappeared and Christianity dominated, and its victory highlights a moment of defining importance, not just in the development of Rome, but also of our modern world.

It is almost certainly no coincidence that a full-sized church was built on the footprint of this humble Christian temple, soon after Emperor Constantine had declared the Roman Empire to be a Christian one in the 4th century. The extravagance of the 12th century basilica – still managed by Irish Dominicans – that would finally be built on top of that one was a future that those worshipping in secret two layers below could scarcely have imagined.

Historians typically go about their task chronologically, starting from the past and working their slow and methodical way towards the present day. In Rome, however, we can do exactly the opposite. In San Clemente in Laterano we can pick our way backwards from the modern city into a multitude of pasts, each more obscure than the previous, and as we descend we gain an unparalleled insight into the complex and unpredictable ways in which Rome came into being, and how it has developed over the passage of the centuries.

This place is simply unmissable.