Several times every week urban speleologist, Signor Quaranta, a slender Neapolitan with lots of energy and funny stories takes groups from Caffè Gambrinus up a narrow street and through double doors that say “Napoli Sotterranea.” From a whitewashed hallway you descend 118 stairs that spiral down past a small chapel, thence to an open space with rows of chairs, an ancient aqueduct.

It was the Greeks who first harnessed the springs from the foot of Mount Vesuvius and channelled the water into these underground cisterns, some as deep as eighty metres. Neapolitans used the cisterns as drinking water all the way up until the 1800s.

Now it’s your chance to experience some of the fifteen kilometres of underground made of porous tuff stone. The ceilings often drip with water due to the humidity. The moist environment is supposedly healthy for respiration, helping (and possibly curing) people with asthma.

World War II graffiti can be seen throughout this maze of narrow passageways and huge halls. Thousands hid here waiting for the war to end. Above an alcove, graffiti commemorates the day two people were married under a tuff arch in 1943. Another room has graffiti that reads: “Women are the way to true happiness.”

Successive small spaces return you to the hollow space with chairs. Signor Quaranta turns off the lights for a few moments so that you can sit in the pitch black and in silence – an odd feeling when Naples bustles with frenetic activity above. This tour is especially welcome during the hot summer months, the temperate climate of the parallel city making it the most comfortable spot in Naples.

Guided Tours of Napoli Sotterranea: Thurs at 2100, Sat at 1000, 1200 and 1800, Sun and Holidays at 1000, 1100, 1200 and 1800. Meet at Piazza Trieste e Trento square (Bar Gambrinus). Excursions last about 60 minutes.