In 1264, Obizzo d’Este prevailed over the rival Salinguerra family of Ghibelline allegiance and for over three centuries the political scene in the city and its territory was dominated by the house of Este. This political and administrative continuity made the splendour of Ferrara and the Estense court grow until it occupied a recognised space among the most prestigious European courts.
The Castle of San Michele was built in 1385 following a violent uprising by the people of Ferrara, exhausted by hunger and oppressed by taxes. It was built by order of the Marquis Niccolò II d’Este who commissioned the architect Bartolino da Novara. The Castle was constructed close to the northern wall of the city, where the gate and the Rocca dei Leoni already stood. Three towers were built around the fortress, forming a quadrangle with a courtyard in the centre, connected by low buildings.
The entire building was then surrounded by a wide moat connected to the network of canals which ran through the city at that time.
It was only at the end of the fifteenth century with Ercole I d’Este that the Castle was raised by one level and became the seat of the court. From 1492, with the creation of the Addizione Erculea (the great urban plan of Biagio Rossetti) the city doubled its boundaries to the north and the Castle could now be found at the centre of the city.
Starting in 1505 with Duke Alfonso I, the Via Coperta (a covered bridge that connected the Castle to the Ducal Palace) became another wing of the palace, where Alfonso created the famous “Camerini” (Chambers) which housed his prestigious art collection.
In 1554, after a serious fire, renovation work began that, thanks to the intervention of Girolamo da Carpi, radically transformed the appearance of the Castle from military to courtly, first with the removal of the medieval battlements and their replacement with elegant marble balustrades and then with the construction of the terraces, which animated the building and invited contemplation of the landscape where the dense network of urban gardens presented a prelude to those of the equally extraordinary Delizie.
In 1598 the Este family had to leave Ferrara because of the lack of a legitimate heir recognized by the Church. After the devolution of the city to the Papal State a succession of Cardinals settled in the Castle where they remained, essentially, until the unification of Italy.
In 1874, the Provincial Administration purchased the Castle at an auction for 110 thousand lira. Over the past forty years successive cycles of renovation have restored the original rooms of the monument which have gradually been made accessible to the public.