Beneath Rome lie 60+ catacombs — 600km of tunnels, 750,000+ graves carved in volcanic tufa (2nd-5th century AD). 6 are open to visitors. ALL require guided tours (30-40 min). Rome guide →
1. San Callisto (Via Appia Antica): THE most important — 20km tunnels, 16 popes buried, Crypt of Santa Cecilia. €8. Closed Wed. 2. Domitilla (Via delle Sette Chiese): LARGEST — 17km on 4 levels, 150,000 graves, underground basilica. €10. Most atmospheric. Closed Tue. 3. Priscilla (Via Salaria): OLDEST known Madonna depiction (3rd century). €10. Closed Tue. 4. San Sebastiano (Via Appia): The ORIGINAL — the word "catacomb" comes from HERE. Pilgrims' graffiti for Sts Peter & Paul. €8. Closed Sun. 5. Sant'Agnese (Via Nomentana): Smaller + Mausoleum of Santa Costanza (stunning mosaics). €8. 6. Jewish Catacombs Villa Torlonia: Menorahs + Hebrew inscriptions. By appointment only — contact Jewish Community of Rome.
Practical: Guided tours every 20-30 min, multiple languages. 15-16°C underground — bring a layer. No photography. Combine: San Callisto morning → Via Appia bike → San Sebastiano afternoon. Or: Domitilla + San Clemente underground for full "underground Rome" day.