The 121 stairs lead to Naples' underground passages buried 30-40m below in galleries of tufa that the Greeks dug in the 4C BC for the construction of the boundary walls of the city. The Roman Aqueduct carried water into the city until 1885. The route then leads to several cisterns built by the Greeks, including one which was transformed into a wine cellar and used by the San Gregorio Armeno Cloister until 1952. The visit ends with a Roman theatre (1C-2C), discovered in 2002.