Basilica di San Clemente

Upper Church

1108–1123 AD

Levels

3 stacked layers

Oldest Layer

1st century AD

Entry

Free / €10 underground

Visit Time

1–1.5 hours

Metro

Colosseo (Line B)

Why Visit Basilica di San Clemente?

Rome is the only city in the world where you can walk vertically through history — and San Clemente is where that promise is most literal. In 90 minutes you descend through a glittering medieval basilica, past 11th-century frescoes with the earliest written Italian, and finally into a 2nd-century pagan temple where Roman soldiers worshipped a bull-slaying god by torchlight. You can hear an ancient stream still running 18 metres below the Colosseum's nearest neighbour. €10 underground, free upstairs.

Three Stacked Layers

12th-century basilica → 4th-century church → 1st-century Roman insula and Mithraeum.

The Best Mithraeum in Rome

The most intact Mithraic sanctuary in the historic centre, with original altar and benches in situ.

Tree of Life Apse Mosaic

The 1120s gold-and-green mosaic of the Crucifixion — one of the great masterpieces of medieval Roman art.

Calm 5 Minutes from the Colosseum

A quiet refuge ten minutes' walk from the busiest site in Rome — and rarely more than half-full.

Exploring the Three Levels

San Clemente is best understood as an archaeological layer cake. Start at street level and descend through time — from the medieval present down to imperial Rome. Each level reveals a different chapter of the city's 2,000-year story.

Level 1: 12th-Century Basilica (Ground · Free)

• Apse Mosaic — the gold-and-green 'Tree of Life' Crucifixion mosaic, swirling acanthus vines, birds, deer drinking from rivers of paradise
• Schola Cantorum — the original 6th-century marble choir enclosure, salvaged from the lower church and reassembled here
• Cosmati Floor — geometric polychrome marble inlay typical of 12th-century Roman basilicas
• Chapel of St Catherine — early 15th-century frescoes by Masolino da Panicale and (debated) the young Masaccio

Level 2: 4th-Century Church (Underground · €10)

• Ancient nave — walk through the original early-Christian basilica, used continuously from the 4th century until 1084
• 9th–11th-century frescoes — the Legend of St Alexis, the Mass of St Clement and the famous Sisinnius cycle
• The 'Sisinnius Fresco' — contains some of the earliest written vernacular Italian, with surprisingly crude colloquial insults
• Original columns and brickwork — the bones of the church before it was buried and built over

Level 3: 1st-Century Roman Buildings (Deepest)

• The Mithraeum — a 2nd-century sanctuary with the original altar relief of Mithras slaying the cosmic bull, flanking torchbearers Cautes and Cautopates, and stone benches for initiates
• Roman insula — remains of a 1st-century apartment-and-warehouse block, with vaulted brick rooms
• Triclinium — the long vaulted room beside the temple, generally interpreted as a space for communal gatherings
• Possible imperial mint building — large industrial chambers possibly linked to Domitian's mint

The Underground Stream

• Constant running water 18 metres below street level — listen at the deepest point
• Ancient drainage that probably feeds the Cloaca Maxima, Rome's antique sewer
• Atmospheric soundtrack to the Mithraeum — a near-mystical effect
• Natural climate control: lower levels stay around 14 °C year-round (bring a layer)

Hidden Details to Notice

• Stratification — see how each century was built directly on top of the previous
• Spolia and reuse — many marble fragments in the upper basilica come from the lower church
• St Cyril's tomb — the apostle to the Slavs, who brought Clement's relics back to Rome in 869, is buried in the lower church
• Irish Dominican stewardship — the basilica has belonged to the Irish Dominicans since 1677, who began the excavations in 1857

2026 Opening Hours

Upper basilica (free)

• Mon–Sat: 09:00–12:30 · 14:00–18:00
• Sun: 12:00–18:00 (services in morning)

Underground excavations (€10)

• Mon–Sat: 09:00–12:30 · 14:00–18:00
• Sun & holidays: 12:00–18:00
• Last admission 12:00 / 17:30

Closed 25 December, 1 January and during Holy Week services. Roma Pass NOT valid (private Dominican site).

The Mithraeum: A Bull Temple Beneath the Basilica

On the deepest level of San Clemente — roughly 18 metres below modern Via Labicana by most published estimates — sits a small vaulted chamber, one of the few Mithraea still visible in situ in central Rome. Built around 200 AD inside the courtyard of an existing Roman insula, the sanctuary is barely 9 metres long and 6 wide, with stone benches running along both side walls where initiates reclined for ritual meals.

At the far end stands the original marble altar, carved on its front face with the canonical scene of Mithras tauroctony: the young god, in Phrygian cap, kneels on a bull and plunges a dagger into its neck while a dog and a serpent leap up to drink the blood and a scorpion attacks the bull's testicles. Flanking the altar relief are the twin torchbearers Cautes and Cautopates, symbolising sunrise and sunset. Above, a vaulted ceiling pierced with seven niches represents the cosmos and the seven planetary spheres through which initiates ascended.

The mystery cult of Mithras flourished in the Roman Empire between roughly 100 and 400 AD, is generally associated with soldiers and traders in the surviving evidence, and admitted only male initiates through seven graded degrees. It vanished after Theodosius's anti-pagan edicts of the 390s — the same decade in which the Christians next door began converting the upper insula into a church. The two religions literally lived on top of each other for a generation.

The Sisinnius Fresco: Earliest Written Italian

On the wall of the buried 4th-century church, one fresco panel (c. 1080) shows the Roman pagan nobleman Sisinnius trying to arrest St Clement and instead finding himself dragging a heavy column. Speech bubbles emerge from the figures' mouths — and they are written not in Latin but in colloquial early volgare italiano, the spoken vernacular that would eventually become Italian.

The most-quoted line, shouted by Sisinnius at his straining servants, is "Fili de le pute, traite!" — politely translated as "Pull, you sons of bitches!" — and is taught in Italian universities as the earliest surviving written sentence in vernacular Italian outside legal documents. The contrast with the Latin liturgical inscription beside it ("Duritiam cordis vestri…") is one of the most poignant document-pairs in European linguistic history. Don't miss it: it's the second fresco on the right as you enter the lower nave.

The Tree of Life Apse Mosaic

Completed in the 1120s, the mosaic that fills the apse of the upper basilica is one of the supreme achievements of medieval Roman art. At its centre Christ is crucified on a tree whose roots and branches spread outward as great spirals of green acanthus, populated with birds, deer, the Four Doctors of the Church, peasants tending flocks and tiny scenes of everyday 12th-century life.

The iconography is deliberately ambiguous: half Crucifixion, half Tree of Life from the Book of Genesis, with the Christianised vine of Isaiah grafted on. The dense gold ground and the sinuous Byzantine line betray contact with Constantinople via Sicily; the cheerful naturalism of the everyday vignettes is unmistakably Roman. Stand in the central nave and let your eyes travel slowly outward from the cross — the mosaic was designed to be read as a single 7-metre-wide poem.

The Irish Dominicans & the Excavations

San Clemente has been Ireland's national church in Rome since 1677, when Pope Innocent XI assigned the basilica to the Dominican friars exiled by the English Penal Laws. The Irish Dominican Province has run it continuously ever since — making it one of only two Roman basilicas under permanent foreign stewardship.

In 1857 the Irish prior Father Joseph Mullooly began digging beneath the upper basilica and discovered the buried 4th-century church with its frescoes startlingly intact. Excavations continued through the 1870s — eventually reaching the Mithraeum and the Roman insula — and conservation work has never stopped. Ticket revenue supports the basilica and archaeological site. This is one of the few major Roman sites where ticket revenue stays on the premises.

Best Time to Visit in 2026

Tue–Fri 09:00–10:30 (best)

Walk in straight from the Colosseum's 09:00 opening, before tour groups arrive. Underground office opens at 10:00.

Late afternoon 16:00–17:30

Quiet, atmospheric, and the apse mosaic catches the warmest natural light through the upper windows.

Rainy or hot days

The lower levels stay at 14 °C year-round — a perfect refuge from a Roman August heatwave or a winter downpour.

Avoid

Sundays before 12:00 (closed for Mass), the 12:30–14:00 lunch closure, and Holy Week mornings (limited access for services).

San Clemente vs Other Underground Rome Sites

San Clemente offers the deepest descent, the broadest chronological range and an in-situ Mithraeum — for a €10 timed ticket. It is the single best underground site in central Rome for first-time visitors.

Common Mistakes to Avoid

❌ Visiting only the upper church

The free upper basilica is beautiful, but the entire reason to come is the underground. Always pay the €10 — it is one of the best-value tickets in Rome.

❌ Trying to use the Roma Pass

The basilica is run by the Irish Dominicans, not the state. Roma Pass and OMNIA Card are not valid for the underground — pay separately.

❌ Showing up at lunchtime

Both the upper basilica and the underground close for the 12:30–14:00 lunch break. Plan around the lunch shutdown or you will be turned away.

❌ Photographing underground

Strictly forbidden to protect the fragile early-Christian frescoes. Phones must be put away on the staircase. Take your photos in the upper church only.

❌ Going underground in a sleeveless top

The lower levels stay at 14 °C year-round, even in August. Bring a light layer, and remember the dress code (covered shoulders and knees) for the upper church too.

❌ Skipping the Sisinnius fresco

It is small and easy to walk past — but it contains the earliest known written sentence in colloquial Italian. Look for the second fresco on the right as you enter the 4th-century nave.

Colosseum Tickets to Book Same Day

San Clemente is ten minutes' walk from the Colosseum and most visitors combine the two in a single morning. Colosseum entry requires a timed-slot ticket booked in advance — here are the best 2026 options:

Colosseum Priority Entrance

Best for: First-time visitors

Skip-the-line access to the Colosseum with entry to Roman Forum and Palatine Hill included. Perfect for first-time visitors.

• Skip-the-line entry
• Colosseum access
• Roman Forum included
• Palatine Hill included

🎟️ Compare Prices:

Colosseum Guided Tour

Best for: History enthusiasts

Expert-led tour with professional guide sharing gladiator history, architecture secrets, and ancient Roman stories.

• Professional English-speaking guide
• Skip-the-line entry
• In-depth historical commentary
• Small group experience

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Colosseum Arena & Underground

Best for: Unique experience seekers

Walk where gladiators fought on the arena floor and explore the underground chambers where they awaited their fate.

• Arena Floor access
• Underground chambers access
• Roman Forum & Palatine Hill
• Expert guided tour included

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Pair Your Visit

San Clemente takes 90 minutes — pair it with one of these nearby sites for a perfect half-day in the Colosseum / Lateran area:

Highlights Checklist

Getting There in 2026

🚶 On foot (best)

10-min walk east of the Colosseum exit on Via San Giovanni in Laterano, then left into Via Labicana. Entrance at no. 95.

🚇 Metro

Line B to Colosseo (8-min walk). Alternatively Line C to San Giovanni or Manzoni (10-min walk from either).

🚋 Tram

Tram 3 stops directly outside on Via Labicana — connects from Trastevere and Piramide.

🚌 Bus

Lines 51, 85, 87 and 117 stop nearby on Via Labicana or Via di San Giovanni in Laterano.

Where to Stay Near Basilica di San Clemente

Looking for convenient accommodation near Basilica di San Clemente? Stay within walking distance to make the most of your visit.

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