This public use persists to the present day: the path above the walls remains heavily trafficked for recreation, and in the summer it also acts as a natural stage for shows and events.

They replaced earlier medieval and Roman fortifications, modernizing and expanding the perimeter protected due to population growth and changing political and economic conditions.

[3] Short sections of the Roman era walls remain preserved today, incorporated into later structures, notably inside the church of Santa Maria della Rosa and in the basement of the Baluardo di San Colombano.

These walls expanded to include areas of the city that had grown since Roman settlement with the economic development of Lucca as a stop on the Via Francigena.

Around twenty four semicircular turrets were also built with the same technique and therefore perfectly integral with the curtains and open towards the interior, characterized the appearance of the city, preserved in numerous pictorial representations.

The development of the city was hindered in all other directions, to the south by the marshes and the proximity to the arch-rival Pisa, to the west by the presence of the Prato del Marquis, to the north by the ever threatening Serchio River, so the only medieval expansion of the city walls was seen in the northeast sector, where there were two additional gates built, San Gervasio and Portone dei Borghi, between which there were informally built fences and towers following the contours of the ground.

In particular, the tall, thin medieval walls were effective for preventing infantry attacks, but were wholly inadequate to resisting cannon fire, which by that time had become a mainstay of siege warfare.

The real phase of construction began in the first half of the 16th century, with curtain wall segments flanked by large bastions allowing for reverse fire.

The construction of the current structure began with Jacobo Seghezzi in 1544, an architect who was soon joined by famous military engineers such as Galeazzo Alghisi and Baldassarre Lanci, who remained in Lucca's pay between 1547 and 1557, before moving on to the service of the Grand Duke of Tuscany.

In 1589 Alessandro Farnese was consulted, and he provided a plan that all subsequent engineers generally adhered to, up to Paolo Lipparelli who in the five-year period 1645-1650 completed the enormous construction.

The conservation of the moat (although deprived of the counter-shoe) and of some external works (a very rare case in Italy), which currently perform the function of a grandiose public green park surrounding the historic center, is due to this civil use.

This function was officially recognized in 1840 with the construction of a café on the Baluardo di Santa Maria then moved further back to create space for the Statue of Vittorio Emanuele II by Augusto Passaglia placed in 1885.

This naturalistic solution, consisting of earthworks and trees, has made it possible to make the structure perform a hydrological function, to drain the ground against landslides and slips and to distribute the loads over large surfaces.

The structure was based on a large mass of pressed and beaten earth together with dried plant materials, enclosed inside by a brick and stone outer layer.

The terrariums were mainly coordinated by Vincenzo Civitali, who underlined their importance with respect to the classic brick and stone walls, which had become obsolete in the era of cannons.