Castello owes its name to a fortification present in the early Middle Ages on the island of Olivolo, today better known as the island of San Pietro di Castello. At the beginning it was divided into the Gemine islands and the island of Olivolo, later united to form the current district.
Here is still the Basilica of San Pietro di Castello which was the bishop's seat until 1807, the year in which Napoleon gave orders to transfer it to the Basilica of San Marco, until then the personal chapel of the Doge and open to the people only for truly unique events or special.
It is the only one of the sestieri not to be bathed by the Grand Canal, the second in population and the largest. Seeing it from above it represents the tail of Venice, comparing it to a fish, whose particular shape of the city reminds it.
It borders to the north-west with the Cannaregio district between the Fondamente Nove and Campo Santa Marina, and to the south-west with the San Marco district between the Parish of San Lio and Piazza San Marco. It also joins the San Marco district by means of the Paglia bridge by communicating the pier of Piazzetta San Marco with the Riva degli Schiavoni, overlooking the Rio di Palazzo, adjacent to the Palazzo Ducale.
While it connects to the Cannaregio district with the bridge of Santi Giovanni e Paolo which passes the Rio dei Mendicanti a few steps from the monument dedicated to Bartolomeo Colleoni del Verrocchio.
It is here, specifically in San Pietro di Castello, that the Festa de San Piero de Castéo takes place every year: one of the most popular and true festivals in the city. The outline in which it takes place is absolutely indescribable, alive and full of energy.
It is also here that the Arsenale of Venice resided and still resides, literally vital for the Serenissima during all its activity. Here real fleets of ships were built, both merchant and war, at still unbeatable rates, anticipating centuries the modern concept of factory and assembly line with standard components, giving up to 5% of the entire population to work 'era.
Today owned by the Italian Navy, a huge complex of buildings partly designed and built by Sansovino, it occupies a significant portion of the district and about one sixth of the entire surface of the island city nucleus. A few steps from the Arsenale there is today the Naval History Museum, where, among others, an exhaustive and detailed model of the Bucintoro is still preserved.
It is also surely one of the greenest areas of Venice, since between the Gardens and the island of Sant'Elena you can enjoy a wonderful panorama of green sea, tall old trees, shrubs, flowers, gazebos, games for children and a splendid view over the part of the lagoon that goes from the Island of San Giorgio Maggiore to the Lido of Venice, being able to see the other islands such as that of San Servolo, once a mental hospital and today hosting a modern structure of the International University of Venice.
This is the district where the Civil Hospital of Saints San Giovanni and Paolo also resides, name inherited from the nearby Basilica of the same name, built on the ashes of the original Scuola Grande di San Marco that Napoleon later adapted into a military hospital and today, in fact, a civil hospital .
Not far from the Arsenale you can also walk on one of the widest widest in the whole city, the Riva degli Schiavoni - whose name historically indicated the area where the ships of the Dalmatian merchants, at the time Schiavonia, moored to lead the exchanges and trades with the Venetians - where together with the original Riva dell'Impero - today Riva dei Sette Martiri in memory of the partisans who fell during the Second World War - until not too many years ago cruise ships, military ships and even some also docked submarine. Also here is the ISMAR - Institute of Marine Sciences of the CNR.