A small entrance inside church of San Paolo Maggiore leads to a tour through the cavities of Naples. The route goes through a narrow zone that speleologists say is the Augustan aqueduct, which carried water over the 170 kilometre journey from the Sarno to the wells of the city. Underground visitors can see tunnels, cisterns and foundations whose purposes are not always known. The tour, which lasts 2 hours, is preceded by a slide show and a historical talk and ends with visits to the experimental greenhouse that exploits the underground humidity. Tours need to be booked in advance.
