Basilica of San Clemente Historical Timeline

Last updated on September 29, 2026

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A private house that became a church, a church that became a foundation, and a foundation nobody demolished — which is why all three are still here.

Chronology

1st century A.D. — the site holds an industrial building, probably the imperial mint of Rome, built or remodelled during the Flavian period. Structural impact: massive foundations are laid that later builders will never remove. What you see today: the lowest level of the visit, and the reason there is anything to stand in at all.
1st century A.D. — the site is used for clandestine Christian worship in what had been a private home, a practice that continues as the community grows. Structural impact: establishes the continuity of use that every later building here inherits. What you see today: the reason a church stands on an industrial block rather than on a temple platform.
4th century — the lower level of the industrial building is filled in with dirt and rubble and its second floor remodelled; by the sixth century the site has become a grand public basilica. Structural impact: the Roman building becomes a foundation rather than a ruin, and the first church is raised on top of it. What you see today: the middle level, and the fill that preserved the Roman rooms beneath by burying them.
9th century, and ca 1080–99 — two campaigns of restoration in the lower basilica. Structural impact: the church is decorated rather than rebuilt, which is why its paintings survive in sequence. What you see today: frescoes of the eighth to eleventh centuries on the middle level.
Last third of the 11th century — a lay couple, Beno de Rapiza and Maria Macellaria, sponsor four of the largest frescoes, on the life, miracles and translation of St Clement. Structural impact: lay patronage on a scale usually reserved to clergy. What you see today: the best-known paintings in the lower church, and the names of the two ordinary people who paid for them.
1099 — Cardinal Rainerius of St Clemente is elected Pope Paschal II in the lower basilica, the last major event to take place there. Structural impact: marks the end of the lower church's active life. What you see today: a dated end point for the level you are standing in.
ca 1099–1120 — the present basilica is rebuilt in one campaign by Cardinal Anastasius. Structural impact: the old church is not demolished but filled and built over, which is the single decision that made this site what it is. What you see today: the upper basilica, and everything beneath it, preserved by being buried.
12th century — the schola cantorum is assembled incorporating marble elements from the original basilica, and the apse is covered with mosaics on the theme of the Triumph of the Cross. Structural impact: the new church is furnished with the old one's fabric. What you see today: the enclosure in the nave and the apse mosaic, a high point of twelfth-century Roman work.
1667 — the Irish Dominicans take ownership of the basilica and the surrounding complex. Structural impact: a single community takes long-term custody, which is why the excavation programme of the next two centuries happened at all. What you see today: they still own and run it.
1715 — Pope Clement XI affixes a plaque in the atrium praising the basilica. Structural impact: papal attention precedes a rebuilding of the front. What you see today: the plaque, and the facade that followed it.
1719 — a new facade by Carlo Stefano Fontana is completed. Structural impact: the medieval church acquires an eighteenth-century front. What you see today: the street elevation, which tells you nothing about what is behind it.
1860s — Joseph Mullooly, Prior of the Irish Dominican house from 1847 to 1880, discovers the archaeological traces of the basilica's history. Structural impact: the lower levels are rediscovered and excavation begins. What you see today: the entire underground visit exists because of this one man's digging.
1867 — the main cult room of the Mithraeum, the speleum or "cave", about 9.6 metres long and 6 wide, is discovered; it cannot be properly investigated until 1914 for lack of drainage. Structural impact: water, which has shaped this site since antiquity, delays its own excavation by nearly fifty years. What you see today: the Mithraic temple, and the running water you can still hear beside it.

Verified against Wikipedia, September 2026.

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Sources & verification Covers the sourced claims on this page.

Checked against Wikipedia — The church was transformed over the centuries from a private home that was the site of clandestine Christian worship in the first century to a grand public basilica by the sixth century, An industrial building, probably the imperial mint of Rome from the late first century A.D. onwards because a similar building is represented on a sixteenth-century drawing of a fragment of the Severan marble plan of the city, was built or remodelled on the same site during the Flavian period, At some time in the fourth century the lower level of the industrial building was filled in with dirt and rubble and its second floor remodelled, Restorations were undertaken in the ninth century and around 1080 to 1099, and the last major event to take place in the lower basilica was the election in 1099 of Cardinal Rainerius of St Clemente as Pope Paschal II, Four of the largest frescoes in the basilica were sponsored by a lay couple, Beno de Rapiza and Maria Macellaria, at some time in the last third of the eleventh century, and focus on the life, miracles and translation of St Clement, The current basilica was rebuilt in one campaign by Cardinal Anastasius from about 1099, and a now-outdated hypothesis held that the original church had burned out during the Norman sack of the city under Robert Guiscard in 1084, but no evidence of fire damage in the lower basilica has been found to date, The twelfth-century schola cantorum incorporates marble elements from the original basilica, and the episcopal seat stands in the apse, which is covered with mosaics on the theme of the Triumph of the Cross that are a high point of Roman twelfth-century mosaics, Irish Dominicans have owned the Basilica of San Clemente and the surrounding building complex since 1667, On one wall in the atrium is a plaque affixed by Pope Clement XI in 1715 praising the basilica, and Carlo Stefano Fontana was selected as architect and erected a new facade, completed in 1719, The archaeological traces of the basilica's history were discovered in the 1860s by Joseph Mullooly, Prior of the house of Irish Dominicans at San Clemente from 1847 to 1880, The main cult room, the speleum or "cave", which is about 9.6 metres long and 6 metres wide, was discovered in 1867 but could not be investigated until 1914 due to lack of drainage (September 2026).

Basilica of San Clemente Historical Timeline

Chronology

External Resources

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