The peninsula west of Naples, on the northern side of the bay, is unusual because it consists of a large number of overlapping craters of very young and partly still active volcanoes. This gives rise to very fertile soil and the presence of a large number of hot springs, which, together with the great natural beauty of the area made it attractive for settling. For this reason ancient Greek Colonies such as Cumae and Neapolis were built here but also Puteoli (Port Iulious), the most important commercial harbour during Augustus time.
The entire Naples area is a geothermal region with deep veins of yellow tuff, a strong, durable tuffaceous volcanic sandstone formed over millennia. Tuff is strong and easily worked, making it an ideal building material. After the tuff was quarried it was used as building material starting from ancient Greeks who built the city walls, up to the Norman (1037 AD), Angevin (1266 – 1372 AD), Aragonese (1443 AD) periods, and the Spanish vice royalty (1503 AD).
The resulting caverns were later used to form water reservoirs into which water was diverted from the aqueducts. These provided fresh water to the villas and palaces above. Well shafts were also dug offering community access to reservoirs below.
Naples was founded by Greeks around 470BC and has been continuously inhabited growing in size and in population density. The urban growth has been uninterrupted ever since its foundation, nevertheless instead of expanding in space, for centuries the settlement has been growing on itself, occupying more and more any areas left free by former civilisations inside the town walls. Thus, the city reached a very high density already since ancient times.
The name of the city comes from the Greek Neapoli (Νεάπολη = new city).