On Via dei Tribunali and a few steps from San Gregorio Armeno, you’ll find the entrance to Napoli Sotterranea (Naples Underground). It’s in Piazza San Gaetano, n.68.

Naples Underground (Napoli Sotterranea) is a must-see tour that takes you on a journey through the city's hidden history. Tours begin at street level and you descend 40 meters below, walking through passages and exploring ancient aqueducts, Roman theaters, caverns used as bomb shelters during WWII, and other captivating sights. You’ll walk by candlelight in one small stretch of tunnels; however, this passage is completely optional and if you’re uncomfortable with enclosed spaces you can opt out. The Naples Underground tour is truly unique and a great way to experience the fascinating culture and history of the city.