The English version has been carried out by the English department of liceo classico scientifico Francesco Sbordone
Naples and its waters: a 2700 year long history
Neapolis and the Bolla aqueduct:
The morphology of the places and the hydrography
The particular geo-morphological conditions undoubtedly influenced the location of urban aggregates and their development over the centuries. The ring of hills surrounding the centre of Naples must have appeared much more rugged than it appears today. With some reliability, the first topographical representations dating back to the 16th century, still retain the original characteristic morphology of the places, although altered by the westward urban expansion.
From the hilly system of Vomero and Capodimonte torrential watercourses descended into the valley, along the current Petraio, via Cacciottoli, the Cavone, Salvator Rosa, S. Teresa al Museo, via Stella, via Vergini.
These waterways flowed in two directions and their bed can be still identified in the current Via Foria and Via Pessina.
The valleys created by these waterways - primarily that of Via Foria - determined the natural isolation of the coastal area; and it was exactly in this area, and precisely in the highest part of the plain that extends between the crater amphitheatres of the Campi Flegrei and Vesuvius, which Neapolis (ca. 470-460) developed.
The reason for this localization is double. Firstly, the area was naturally protected by hills; secondly, unlike Pizzofalcone, the conditions existed there for the development of a real urban system.
The area bordered, on one side, the extension of the watercourse along via Foria, which in the area of the current via Cirillo was divided into several branches producing, together with Rubeolo’s spring, a vast marshy area (an age-old obstacle for the expansion of the city towards the east). On the other hand, the limit of the urban area was marked by the course of a small river with a fairly regular course, which flowed along the current streets of Pessina, S. Anna dei Lombardi, Medina and finally flowed into the plain where Piazza Municipio is today, in the area located where the first port structure of the city was built.
The waters of the Clanis, instead, while pouring into the vast swamp lying between Neapolis and the inland region hindered the communications between the coastal area and the hinterland.
The entire coast was morphologically shaped up in a very different way compared to how it appears today, since multiple episodes of bradyseism and sea expansions have irregularly transformed the coast.
The port, as already mentioned, was much further back than today. In the east, the coastal advancement occurred to a modest extent; in the stretch of coast that goes from Castel dell'Ovo to Mergellina, the siltation was instead massive, while in the extreme parts of Posillipo it was the sea that significantly moved forward compared to the coast.