Genoa, like many other ancient villages, was forced, since the most remote times, to protect itself with defensive walls, to protect itself from the attacks of pirates and other enemy populations.
The original nucleus of the city was focused on the hill of Sarzano, and was surrounded by a first circle of walls. Over the centuries, the town developed towards the west, while the defensive walls were now enlarged, now built ex-novo around it. Consequently, the boundaries of the city also changed.
In 1155, for example, Genoa was enclosed within the so-called “Barbarossa walls”, i.e. the area between the current Piazza Dante and Via delle Fontane, on the border with Prè: in short, a good part of today’s historical center. Identifying traces of those ancient walls, today is almost impossible: very often, during the expansion, civil buildings used the wall structures of the walls, erasing, in this way, the testimonies. Even in the sixteenth century, the defensive walls finished in 1536 (now called Old Walls) followed the course of the town.
In that period, the area of the city was included within the current areas of Ospedale Galliera, Acquasola, Villetta Dinegro, Castelletto, Albergo dei Poveri, corso Ugo Bassi and piazza Principe, while the sea side, even if fortified, represented a natural defense.
But in 1625, the Duke of Savoy, with the help of France, invaded the domain of the ancient Republic of Genoa, threatening also the capital.
The wall of 1536 had become, in a certain sense, “dangerous”, as well as obsolete and inadequate to the progress made in the field of artillery; it, in fact, faithfully followed the perimeter of the entire town. The enemy, camping at a short distance from the Walls, would have easily caused damage to the population with the use of artillery. We must keep in mind that, in some points, the houses exceeded the fence.
It was therefore decided to build a new, powerful city wall (the last one), using the natural amphitheater that had its peak on Mount Peralto. From here began two large ridges, which descended towards the sea following the two main valleys, that of Polcevera to the west and that of Bisagno to the east.
The work, called “Mura Nuove”, faithfully followed the course of the original ridge.
Completed between 1626 and 1634, it represented an innovation in the field of fortifications; in this case, in fact, the walls were not built close to the inhabited center, but mostly far from it. With the implementation of the new wall, the western boundary was extended up to the Lanterna, while to the east the Bisagno stream already formed a natural border, so it was sufficient to graft to the sixteenth-century Bastione del Prato (under the Galliera hospital), the new wall descending from the Peralto.
To the north of the city, still enclosed within the perimeter of the sixteenth-century walls, a sort of “free zone” was created, represented by strips and gardens, furrowed by small valleys with streams and scarcely wooded. There were few inhabited houses, at most a few villas and a few convents.
(Taken from “Forti di Genova, storia, tecnica e architettura dei forti difensivi” Stefano Finauri, Ligurpress)