Basilica of San Clemente

The draw

You can walk down through Rome. At street level is a twelfth-century basilica with an apse mosaic that is among the best medieval work in the city. Below it is a fourth-century church with frescoes of the eighth to eleventh centuries. Below that is a first-century Roman street, with a Mithraic temple on one side and a large public building on the other, and you can hear water running through the foundations. Nowhere else in Rome presents its own stratigraphy this plainly.

The problem when visiting

The excavations cannot be entered without booking online. The church at street level is free and open to anyone; the two levels beneath — the whole reason to come — are ticketed and require a reservation. Visitors regularly walk in, look at a nice medieval church, and leave without knowing what was under their feet.

The tactic

Book the excavations before you leave home, then pair the visit with the Colosseum, which is five minutes away. Go down first while you are fresh — the lowest level is dark, damp and narrow — and come back up into the basilica afterwards, which is the right order chronologically and the better one visually. Bring a layer: it is cool below all year.

Skip it if you:

• Cannot manage stairs. There is no step-free route to the excavations, and there was never going to be — they are two levels below a building of the 1120s. The upper basilica is worth entering on its own and is free.
• Have not booked and are here today. The excavations do not take walk-ins. Look at the basilica, which costs nothing, and come back another day.
• Are claustrophobic. The lowest level is a narrow alley between two Roman buildings, low and enclosed, with running water you cannot see.
• Want mosaics rather than archaeology. If it is the twelfth-century apse you came for, that is in the free upper church and you need no ticket at all.

The frescoes are the reason the lower levels are controlled. Eighth- to eleventh-century wall painting in a damp, enclosed space is close to the worst conservation case there is: breath and body heat change the humidity in rooms where humidity is already the standing problem. The booking requirement and the 25-person cap are conservation limits, not queue management. Keep to your time and do not touch the walls.

It is a working church, and the upper level is free because of that. Mass is said here and pilgrims come specifically for it. If a service is under way, the basilica is not a viewing gallery — wait, or come back.

No flash, and no tripods in the excavations. Light is a cumulative dose on pigment, and the passages are too narrow for anyone to step around a tripod.

Book directly with the basilica. The Dominicans run the excavations themselves and take bookings through their own office. Money paid to a reseller for a site with a 25-person cap buys the same slot at a markup and takes revenue away from the community that has maintained the excavation since the 1860s.

Booking is required for the excavations

This is the fact that decides the visit: online booking is required to enter the archaeological excavations. The basilica at street level needs nothing and costs nothing, but the two lower levels — the reason almost everyone comes — do not take walk-ins.

The Secretary's Office can be contacted Monday to Friday from 10.00 to 16.00, closed Saturdays, Sundays and public holidays, at segreteria@basilicasanclemente.com.

Hours

Monday to Saturday: 9.00 to 12.30, last entrance 12.00; then 14.00 to 18.00, last entrance 17.30. Sundays and public holidays: 12.00 to 18.00, last entrance 17.30.

Note the closed middle of the day, which is easy to walk into by accident: the site shuts between 12.30 and 14.00, and the morning's last admission is at 12.00 rather than 12.30.

Ticket & Pass Decision Matrix

Two turnstile rules. First, no booking means no excavations, whatever you are willing to pay at the door. Second, the free under-16 ticket is conditional on an adult ticket being bought with it, so a school group and a family are priced differently on purpose.

What is free

The upper basilica costs nothing. It is a working church with its own liturgical life and pilgrim masses, and entering it requires no ticket and no reservation. That includes the twelfth-century apse mosaic of the Triumph of the Cross, the schola cantorum with its salvaged marble, the Cosmatesque floor, the early Renaissance frescoes and the atrium with Clement XI's 1715 plaque.

Everything below street level is ticketed. There is no free route to the fourth-century church, the Roman alley or the Mithraeum.

What it is like down there

The excavations are reached by stairs, and there is no step-free alternative to them. It is cool and damp at every time of year — the lost waters of ancient Rome still run around the foundations, audibly — so bring a layer even in August. The lowest level is narrow and enclosed.

Come in the morning, before 12.00. That is the morning's last admission, and the site then closes until 14.00. The commonest planning error here is arriving at half past twelve.

August is a good month for this basilica specifically, which is not true of much else in Rome. Two of its three levels are underground and cool, so it works precisely when the Forum and the Colosseum five minutes away do not.

Sundays start late. Opening is 12.00 rather than 9.00, and the church has services — this is a working parish with pilgrim masses, not only a site.

Book as far ahead as you can in spring and autumn. The underground rooms are small and guided groups are capped at 25, so capacity is genuinely limited rather than nominally so.