There are guided tours to see the underground city in Naples. Through one’s naked eye, one can see this hidden city on special winter tours. It includes almost 5,000 years old out caves and recent Roman water systems too. Other than that, the underground cemetery is worth visiting. There are many number of tours held for specific group of people and one is recommended to wear warm clothes as the site is cold.
The Napoli sotterranea tour provide tour to the magnificent church of San Polo Maggiore through the cavities of Naples unravels. There are underground tunnels, foundations and cisterns which one gets to visit through the tour. Apart from this, these tunnels... more are from chronological origin and the use of the tunnel is still in dark. The tour is for two hours and there are also slide shows and s short historical introduction. The tour ends with a visit to an experimental greenhouse which has the same humidity like the underground tunnels.