Basilica of San Clemente: A Journey into Rome's Underground Secrets

In the heart of the capital, just steps from the Colosseum, tucked away in a quiet square, stands the Basilica of San Clemente . But simply calling it a "basilica" is an understatement: it is, in fact, a true "vertical journey" into the memory of Rome, an emotional descent into centuries of history, spirituality, and art. It's no coincidence that it is beloved by pilgrims, scholars, and travelers from around the world: here, more than anywhere else, the city reveals itself as a "living palimpsest," where each era has left a tangible imprint, preserved beneath our feet.

Entering the 12th-century upper church , you're greeted by a solemn and luminous atmosphere: the apse's mosaics gleam with the gold of Paradise, while the 6th-century marble choir, the Cosmatesque floor, and the early Renaissance frescoes remind you that sacred art is an integral part of the structure. But it's as you descend that the wonder begins: beneath the current basilica lies a 4th-century early Christian church , whose charm is preserved in the medieval frescoes, considered among the most extraordinary in the entire European artistic heritage.

And even further down, a final level takes us back to the 1st century AD, when on these lands stood a Roman domus , a mithraeum and a large public building, crossed by the underground waters of ancient Rome, a perfect blend of religion, civilisation and myth, where every stone tells the story of the transition from the Empire to Christianity.

The origins between mystery and faith

The Basilica of San Clemente boasts a history that dates back to the 2nd century AD . At that time, the area was occupied by a patrician house belonging to Titus Flavius Clemens, one of the first Roman senators to convert to Christianity. When Christianity was still persecuted, the rooms of his domus became a secret meeting place for the Christian community. An intimate and risky beginning, which already foreshadowed the spiritual destination of the place.

But Imperial Rome was a melting pot of cults and symbols, and the same space was later transformed into a Mithraeum: a temple dedicated to Mithras , a solar deity of Persian origin, whose mystery cult included initiation rites celebrated in underground spaces. It's surprising today to walk through the ancient corridors and imagine the torches, the ritual chants, the sacred tension of that subterranean world.

With the arrival of freedom of worship, sanctioned by the Edict of Constantine in 313 AD, Christian roots could emerge. Thus, over that house and that Mithraeum, a basilica arose: an official place of worship, consecrated by Pope Siricius, which kept alive the memory of the first Roman believers.

Time, however, did not spare this building: in 1084, the Normans under Robert Guiscard sacked Rome, and the basilica was severely damaged. Its remains were buried under five meters of debris.

But its story didn't end there. Pope Paschal II, a few years later, decided to build a new church right on top of the old one. It was 1108 : thus was born the Upper Basilica of San Clemente, which still welcomes visitors and worshippers today, suspended over centuries of history.

The stages to admire

The Basilica of San Clemente is a vertical labyrinth where eras overlap like the pages of a book written in stone. Each step down is a step back in history, each room a living fragment of Rome's past: the incredible interweaving of overlapping layers offers an unparalleled experience, capable of recounting centuries of faith, art, and urban transformation.

The 12th century Upper Basilica

The journey begins from the basilica visible above ground today, consecrated in 1108, where the gaze is immediately captured by the splendid Cosmatesque flooring , a carpet of coloured marbles arranged in a geometry that dances under the light.

The presbytery is a triumph of sculptures and symbols: the Schola Cantorum with its medieval pulpits, the candelabra for the Paschal candle, and sculpted elements from the older church. But the pinnacle of beauty is reached by observing the large mosaic in the apse : a golden cross stands out against a lapis lazuli sky, surrounded by celestial figures and vines.

In the chapel of Santa Caterina , however, Masolino da Panicale created a cycle of frescoes that represents one of the first sparks of the Italian Renaissance.

The 4th century Lower Basilica

Descending into the heart of the earth, the silence thickens and the light dims. You enter the early Christian basilica built in the 4th century: a place of ancient charm, where the stone evokes the presence of the first Christian communities.

The walls are adorned with frescoes from various periods, from the 8th to the 11th century. One of the most famous is the Legend of Sisinnius , in which an inscription written in primitive Italian depicts a lively and popular scene. Nearby, the tomb of Saint Cyril , apostle of the Slavs and inventor of the Cyrillic alphabet, makes this stop a spiritual reference point not only for Western Europe , but also for the Slavic and Orthodox world.

The Mithraeum and the 1st century Roman domus

One level further down, Imperial Rome comes to life again. In a humid and secret environment, a Mithraeum emerges : a mysterious temple dedicated to Mithras, an oriental deity worshipped by many soldiers and officials of the Empire.

The altar, carved with the scene of the god slaying the bull, is still intact, powerful and symbolic. The temple was built inside an ancient domus, whose structure is still visible: frescoed rooms, a porticoed crypt, and rooms used for ceremonies.

A few steps away, another Roman-era building offers glimpses of the Moneta, the imperial mint, which was probably located in this very area.

Useful information

Visiting the Basilica of San Clemente is an intense but time-consuming experience: the entire tour can be completed in about half an hour , although every glimpse invites you to stop, breathe, and marvel.

Online reservations are required , both to access the excavations and to choose the most convenient time slot. We recommend arriving at least ten minutes before the time indicated on your ticket: access is regulated to ensure everyone's safe, enjoyable, and respectful participation.