The building of Portoferraio on the site of ancient Fabricia with its Roman origins began in 1548 against the background of the conflict between Francis I of France and Emperor Charles V of Spain.
Duke Cosimo I of Tuscany moved resolutely in this match with the aim of obtaining dominion over the Appiani of Piombino principality, that the Isle of Elba was ruled by, from the Emperor.
Cosimo, though not recognised formally by the Emperor, found it necessary to defend and fortify the stretch of sea between Piombino and Elba that was vital for shipping in the Mediterranean.
With the treaties of 1557, Cosimo was to see the recognition of his full rights over the state of Siena together with the town of Portoferraio that was called Cosmopolis after its founder.
The two military architeets Giovanni Camerini and Giovan Battista Belluzzi known as Il San Marino came together over the construction of Portoferraio.
The three forts rapidly took shape: the octagonal tower of the Linguella at the entry to the Darsena and the two forts of Stella and Falcone, on the highest rises controlling the city and looking out from a steep cliff over the open sea.
In the same period, a moat was dug to separate the fortified city from the rest of the island.
This would only be filled in early this century to meet the requirements of new development outside the city under the industrial impetus provided by the establishment of the new blast furnaces.
The nucleus of the city could be considered delineated around 1556 and Cosimo issued a decree for its population.
In the front line on the so called Attack Front, i.e. on the side facing the island, the lay out of defence line was much simpler than the one
that has been handed down to us through a series of alterations that were effected up to the eighteenth century.
The Attack Front steadily grew with a complex series of ramparts and works sloping downwards towards the moat separating Portoferraio from the island.
In addition to the three forts many of the city complexes must originate from its foundation or the year immediately afterwards.
The Porta di Mare (the Sea Gate) opening at the centre of the Darsena, extended in 1737 by Ferdinand II and on the Eastern side, the Porta di Terra (the Land Gate) oriented towards the road connecting with the island form part of the fortification system.
Among the other stuctures originally part of the military apparatus, it is worth noting the Biscotteria, now a municipal building, restructured in the nineteenth century on a site where the furnaces rubbed shoulders with the prisons, the convent of St. Francis, then the de Laugier barracks and now a cultural and conference centre, the Galeazze Arsenal today fitted out as a market.
The churches harking back to the sixteenth century include the Cathedral extended in different stages up to the end of the seventeenth century and, on the Napoleon rise, the Church of the Misericordia erected in 1582 and revamped in the eighteenth century.
Buildings whitin the city walls include the former Carmine Church built in 1718 and converted into the Teatro dei Fortunati (later Teatro dei Vigilanti) in the Napoleonic period, the very old Palazzo Pretorio, revamped in 1787 and Napoleon's residence in 1814-1815 and the lighthouse placed on Forte Stella by Grand Duke Peter Leopold in 1788.