What is the Basilica San Clemente?
The Basilica San Clemente, or “The Basilica of Saint Clement” in English, is a Roman Catholic church dedicated to St Clement (Bishop of Rome in the 1st century AD) with hidden ruins from medieval and ancient Rome.

Basilica of San Clemente History
Pope Clement I, Bishop of Rome in the 1st century AD, was prolific in converting unbelievers to Christianity. One story claims that he was so successful, in fact, that he was denounced to the Roman Emperor Trajan and accused of insulting the pagan gods. The emperor banished Pope Clement from the capital, exiling him to the Crimea and forcing him to work in the mines. Undeterred by his sentence, he carried on his missionary labours, converting huge crowds of locals to Christianity. For his actions, he was ordered to be tied to an anchor and thrown into The Black Sea. This church is dedicated to the martyred bishop and you’ll see his image in several places, including on the gilded, frescoed ceiling.
Though apparently sombre in its exterior, the basilica’s dazzling interior is the most eye-catching in the whole of Rome, with beautiful inlaid marble floors and elaborate frescoes wherever you look. In the apse, or semi-circular dome, there’s a glittering gold mosaic from the 12th century that depicts the crucifixion of Christ, flanked by the Virgin and St John. Whilst within the chapel of St Catherine there are delightful 15th-century frescoes by Florentine artist Masolino da Panicale showing the legend of the saint, including her gruesome martyrdom at the tender age of 18.
Dig a little deeper and you’ll also discover one of the great archaeological wonders of Rome. The choir enclosure in the centre of the church gives you a clue. Engraved on the marble slabs is the monogram of Pope John II, who died in AD 535, making the slabs significantly older than the church itself. In fact, they were recovered from an earlier 4th-century basilica located directly beneath the current church. This earlier structure lay completely hidden until 1857, when it was discovered by an Irish priest and archaeologist, Joseph Mullooly. Descend the stairs off the south aisle and you’ll find yourself in the earlier basilica, decorated with 11th-century frescoes that detail the life of St Clement and the miracles he performed.

Later excavations revealed an even greater surprise: the foundations of an ancient Roman house adjacent to a much larger building, which historians now think is most likely the Moneta or imperial mint of Rome. And there were still more secrets to unearth. Inside the courtyard were the remains of a Mithraeum, an underground temple dedicated to Mithras, an Indo-Iranian deity with a cult of followers in pre-Christian ancient Rome. The temple has been extraordinarily well preserved and still houses an altar, depicting Mithras slaying a bull, an image featured in all Roman Mithraeums.
Down at this level, you can explore the house, temple, and 2000-year-old Roman streets. You can even listen to the water rushing beneath you through the Cloaca Maxima, the ancient sewer system that still operates to this day. San Clemente is much more than a beautiful church. With its secret ruins, it is one of the most important historical sites in the city, and a wonderful place to delve into Rome’s layers of history.
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