Rome has a myriad of underground sites in the centre and in the suburbs, from catacombs and church crypts to ancient Roman villas and pagan temples.

Most of these sites are not open to the public on a regular basis, either because they are too dangerous or because it is not possible to provide staff for visits. Updated news and visiting information can be found on useful websites such as Sotterranei di Roma, Roma Sotterranea, Amici di Roma, Roma Capitale and Beni Archeologi di Roma. 

Acquedotto Vergine
Via del Nazareno 9/a, tel. 060608, website. 
The Aqua Virgo was built in 19 BC mainly to supply the Agrippa Baths in Rome's Campo Marzio district. It still supplies water to the Trevi Fountain today. Group visits only, booking required. 09.00-19.00. The basement of the Rinascente department store on Via del Tritone also houses a 60-m section of the acqueduct. Mon closed. 

Auditorium di Mecenate
Largo Leopardi (Via Merulana), tel. 060608, website.
Located under a public garden in the Esquilino district, this fresco-covered nymphaeum is all that remains of a vast architectural complex belonging to Gaius Maecenas, or Mecenate, an advisor to Octavian and enlightened patron of the arts. Group visits only, for details see website. 

Basilica di S. Clemente
Via Labicana 95, tel. 067740021, website.
A 12th-century basilica built over a fourth-century domus ecclesiae – a church in a private home – for early Christian worshippers. This in turn was constructed over buildings dating from between the first and third centuries AD, including a pagan temple. Mon-Sat 09.00-12.30, 15.00-18.00. Sun 12.15-18.00.  

Catacombs of S. Agnese
Via Nomentana 349, tel. 068610840.
Named in honour of the virgin and martyr St Agnes, these catacombs in the Trieste district date to the second half of the third century. 09.00-12.00, 16.00-18.00. Closed Sun mornings and religious feast days.

Catacombs of S. Callisto 
Via Appia Antica 110, tel. 0651301580.
These important catacombs originated in the second century and occupy some 36 hectares. The four levels of tunnels cover 20 km and are more than 20m deep. Among the thousands of people buried here are ten martyrs and 16 popes. 09.00-12.00, 14.00-17.00, Wed closed.

Catacombs of S. Domitilla
Via delle Sette Chiese 282, tel. 065110342.
Rome's oldest and best-preserved catacombs contains a network of tunnels covering 17km, a second-century fresco of The Last Supper and a fourth-century subterranean church. 09.00-12.00, 14.00-17.00. Closed Tues and 16 Dec-13 Jan.

Catacombs of Priscilla
Via Salaria 430, tel. 0686206272.
Situated near the Villa Ada park, these catacombs comprise a series of labyrinthine tunnels and burial chambers excavated between the second and fifth centuries. 08.30-12.00, 14.30-17.00. Closed Mon and Aug.

Catacombs of S. Sebastiano
Via Appia Antica 136, tel. 067850350.
From the first century this maze of tunnels and caves was used extensively to inter pagans and Christians, including the martyrs Sebastian and Eutychius. 10.00-17.00. Closed Sun and 1-28 Dec.

Capuchin Crypt
Via Vittorio Veneto 27, tel. 0688803695.
The vaults and walls of the four chapels in the Capuchin crypt are decorated with the bones of 4,000 monks who died between 1600 and 1800. Located under the church of  S. Maria della Concezione dei Cappuccini. 09.00-19.00. 

Church of S. Crisogono
Piazza Sidney Sonnino 44, (Viale Trastevere), tel. 065810076.
Underground site including an early Christian church and a third-century Roman house. Mon-Sat 07.30-11.30, 16.00-19.00. Sun 08.00-13.00, 16.00-19.00. Not possible to visit excavations during celebration of Mass. 

Church of S. Lorenzo in Lucina
Via in Lucina 16, tel. 066871494, website.
This underground site was originally thought to have been a Roman house for early Christian worship but recent research indicates that it may have been a pre-Christian temple to Giunone Lucina, the goddess of pregnant women. Tours last Saturday of the month at 16.15. 

Church of S. Nicola in Carcere
Via del Teatro di Marcello 46, tel. 0668892781, website.
The remains of three Republican-era temples, cells and alleys under the altar were once part of the bustling Forum Boarium complex, ancient Rome's cattle market. 10.00-17.00. Wed closed.

Crypta Balbi
Via delle Botteghe Oscure 31, 0639967700, website.
Built over the ancient Roman Theatre of Balbus, this partially-underground museum is dedicated to urban archaeology and the Middle Ages. Tues-Sun 09.00-19.45. Mon closed. 

Domus Aurea
Viale della Domus Aurea 1, website.
Emperor Nero's golden palace was built after the great fire of Rome in 64 AD on a sprawling site in the Colle Oppio area. Guided tours in English Sat-Sun 09.00-16.45. Virtual reality tours Sat-Sun 09.00-18.15 (last admission 17.00). 

Hadrian’s Crypt (Bocca della Verità)
Piazza Bocca della Verità 18.
Under the altar in the church of S. Maria in Cosmedin there is a small eighth-century crypt built to hold relics extracted from the catacombs by Pope Hadrian I. Mon-Sat 10.00-14.00, 15.00-17.30, Sun 12.00-17.30.

Jewish catacombs
Via Nomentana 70 and Via Appia Pignatelli 4.
The are six Jewish catacombs in Rome but not all are accessible. The Villa Torlonia catacombs, on Via Nomentana 70, are the largest and best known, while the Vigna Randanini catacombs, on Via Appia Pignatelli 4, opened to the public for the first time in 2016. For up-to-date visiting information see Catacomb Society website. 

Mithraeum in Circo Massimo
Piazza Bocca della Verità 16, tel. 060608. 
Guided visits for groups only. This five-room mithraeum, at the Bocca della Verità end of the Circus Maximus, is dedicated to the Roman deity Mithras. It dates to the fourth century but was only rediscovered in 1931.

Mithraeum in S. Prisca
Via di S. Prisca 11,  tel. 0639967700, website.
The church of S. Prisca on the Aventine was built over a first-century temple to Mithras. Open on the second and fourth Sunday of every month, for individuals at 16.00, for groups at 15.00 and 17.00. Booking required.

Palazzo Valentini 
Via Foro Traiano 85 (Piazza Venezia), tel. 0622761280, website.
The remains of ancient Roman houses are on permanent display below Palazzo Valentini, just off Piazza Venezia. 09.30-18.30. Tues closed. 

Terme di Caracalla
Viale delle Terme di Caracalla 52, website.
These Roman baths have a maze of underground areas including a gymnasium, changing rooms, frigidarium, tepidarium and caldarium. Open daily, Mon half day. For varying opening times see website. 

Stadium of Domitian
Via di Tor Sanguigna 3, tel. 0668805311, website.
The remains of the Domiziano Stadium, a Unesco World Heritage Site commissioned around AD 80 by Emperor Domitianus, are located about 4.5m under Piazza Navona. Daily 10.00-19.00, Sat 10.00-20.00. Audio guide available.

Vatican scavi
St Peter's Basilica, website.
This Imperial-era necropolis contains the tomb of St Peter. Only private visits on request. Tour groups are composed of approximately 12 people, according to language. For information see website or go to excavations office to the left of the Bernini colonnade in St Peter’s Square. Mon-Fri 09.00-18.00, Sat 09.00-17.00.