Basilica of San Clemente: three layers underground and a Mithraeum

The Basilica of San Clemente (San Clemente al Laterano), five minutes' walk from the Colosseum, takes you down through time on three levels: a 12th-century church, a 4th-century basilica covered with medieval frescoes, and 1st-century Roman buildings with a temple of Mithras. The upper church is free to enter; the underground excavations cost €10 and are booked online. Open Monday to Saturday from 9am to 12:30pm and from 2pm to 6pm, and on Sunday from 12 noon to 6pm, it takes about an hour to visit. The basilica has been in the care of the Irish Dominicans since 1677; one of them, Father Joseph Mullooly, began the excavations in 1857.

Highlights

The 12th-century upper church

You enter through a colonnaded atrium, then into a nave with a Cosmatesque floor. In the centre, the schola cantorum, with its two ambos and its Easter candlestick, was put together in the 12th century with 6th-century marble panels recovered from the lower church. In the Chapel of St Catherine, the frescoes by Masolino da Panicale herald the Renaissance.

The apse mosaic

Against a gold background, a cross bearing Christ and twelve doves rises amid huge acanthus scrolls filled with birds, figures and animals. Below, twelve lambs stand for the apostles. It is one of the richest medieval mosaics in Rome; go up to the balustrade to see the details.

The 4th-century lower basilica

The first level of the excavations keeps frescoes painted from the 8th to the 11th century, including Christ among Angels and Saints and the Legend of Sisinnius (around 1084-1100), whose painted phrases are among the earliest written examples of vernacular Italian. It also holds the venerated tomb of St Cyril, apostle of the Slavs and patron of Europe, credited with the Cyrillic alphabet.

The Mithraeum and the Roman house

Further down, a temple of Mithras from the late 2nd century was set up in the cryptoporticus of a Roman house (domus) from the second half of the 1st century. The altar shows the god slaying the bull, between the worshippers' benches. A narrow passage leads to a large public building, perhaps the imperial Mint, where you can hear an underground spring flowing.

Opening hours and tickets

Upper church: free entry during opening hours. Excavations: €10 full price, €5 for students under 26 with a student card, free for under-16s accompanied by a parent (booked with a full-price ticket) and for disabled visitors and their companion. Online booking, with a date and time slot, is the only way to guarantee entry, as the number of daily visitors is limited. Arrive 10 minutes before the time shown; a leaflet with the route is handed out at the entrance, and the basilica does not offer guided tours.

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