One of the great things about visiting cities as old and constantly inhabited as Naples is that you often get two cities for the price of one. Specifically, there’s a whole other city underneath what is present-day Naples, with underground passages, streets, and markets, some of which date back to ancient Greek times.
The most common way to experience underground Naples is by taking a tour of “Napoli Sotterranea,” or Naples Underground. The narrow passageways and rooms you visit at Napoli Sotterranea are more than 130 feet (40 meters) below street level and some of it dates back 2,400 years. Among the things you’ll find underground are Greek aqueducts, burial chambers, and World War II shelters. There’s even a Greco-Roman theatre underneath what is now a home in Naples.
There are other ways to visit underground Naples, too. Go to the San Lorenzo Maggiore church in the historic center and head downstairs to find an incredible half-excavated Roman market. Head uphill to the Capodimonte toward the Madre del Buon Consiglio church, where you’ll find the Catacombs of San Gennaro, an underground burial site dating from about the 4th century. (San Gennaro, Naples’ patron saint, is now entombed in the city’s cathedral.) Another catacomb, San Gaudioso, was once a separate cemetery but part of the San Gennaro catacombs, and it is also accessible for visits.
Guided tours are required to visit most underground sites in Naples, although you don’t always need to book them in advance. There are regular tours of the most popular sites, with their times (and languages) posted prominently at the entrance. Or, to be sure you’ll get on a tour, you can book a spot on a tour of the Catacombs of San Gennaro before you leave home.