The fortress of San Giovanni Battista or fortress da Basso is a modern fortification work in the walls of Florence. Surrounded by the ring road avenues and part of the Firenze Fiera exhibition complex, today it is the venue for numerous national and international conferences, concerts and initiatives, in addition to the Opificio delle Pietre Dure.
Born with the name of Castello Alessandria, it was built by Pier
Francesco da Viterbo and Antonio da Sangallo the Younger between 1534
and 1537 by order of Alessandro de' Medici. In May 1533 excavations
began, supervised by Alessandro Vitelli and the architect Pier Francesco
da Viterbo. On 15 July 1534 the first stone was laid and in December of
the same year the works of the fortification works were mostly
completed.
The gigantic fortress, pentagonal in shape, was built
with great means and speed to ensure control of the city to the Medici,
who had just returned from the Siege of Florence, to provide
accommodation for a strong contingent of troops, as well as refuge for
the rulers in case of revolt, but also to impress and intimidate the
Florentines with its mass. To accentuate this impression, the side
facing the city was given a monumental aspect by Antonio da Sangallo.
The military role of the fortress was also maintained in the
Lorraine era, when other buildings of architectural and environmental
interest were built, such as the officers' building and a small theatre.
In 1775 de Sade described the Da Basso Fortress as follows on his
trip to Italy: «[…] la forteresse Da Basso ou château
Saint-Jean-Baptiste. C'est un pentagon régulier avec des bons fossés et
un chemin couvert. Il faut voir l'arsenal et la fondrie de canons».
At the time of the demolition of the fourteenth-century walls,
during the period of Florence as capital of Italy, the fortress remained
isolated and its moats were leveled, leading to the burial of most of
the walls.
The Fortress, which like many other similar structures
was never used, remained in the military domain until 1967. In recent
years it was identified as the site of the Florentine trade fair;
consequently a long restoration and adaptation work was undertaken (not
yet completed) which led to the demolition of service structures built
during the use of the fortress as barracks. Thanks to these works, today
the fourteenth-century Porta a Faenza is visible, and to follow the
ancient course of the Mugnone, a stream that flowed in the moats of the
city; visit the interior of the keep and some other structures of a
certain interest, such as the powder magazine.
To host the events
of Firenze Fiera, two new exhibition pavilions were built, named after
the designer, respectively "Spadolini" (Pierluigi Spadolini, 1977) and
"Cavaniglia" (1996).
Inside the fortress there is one of the
headquarters of the hard stones factory with numerous scientific and
restoration laboratories. The Palazzo dei Congressi was built in the
gardens of the facing Villa Contini Bonacossi.
Since the fortification stood on a plain, according to the canons of
military architecture of the time it should have had a regular plan with
fully developed bastions, identical to each other and equipped with
trunnions.
Instead, an irregular pentagonal plan was chosen to
graft the base side into the pre-existing Arnolfi walls; in the center
of this side, the longest, was built the so-called keep, an extremely
original structure which incorporates the ancient Porta Faenza. In
reality it is a platform, that is a sort of mini bastion invented by
Antonio da Sangallo to interrupt too long curtains and guarantee grazing
fire from the artillery.
The structure was therefore of a mixed
type, with the part facing out fully developed and regular, while
towards the city the need prevailed not to invade too much space inside
the walls. A similar plan can be found in the (no longer existing)
citadel of Piacenza, also traced by Pier Francesco da Viterbo.
While Cortina and Bastioni were built with cheap bricks (which
incidentally were better able to absorb artillery shells) the Mastio was
built in pietra forte, and the walls were carved with a decorative motif
of balls, alluding to the Medici coat of arms, and diamonds ; similar
decorative parties were common in the Renaissance (think of the Palazzo
dei Diamanti in Ferrara) but were never again used on this scale in a
military work. Today, inside the Platform, it is possible to visit the
octagonal hall, equipped with an extraordinary herringbone brick vault,
which was part of the monumental access route to the fortress. Some
surviving watercolor drawings from the various stages of the design are
considered to be among Antonio's finest drawings.