The largest of the six sestieri of Venice, Castello is home to the famous Arsenale, the first animated production line that was capable of building a ship for war service in a single day.  The area was a ‘gateway’ to the Adriatic sea during the rise of the Republic, especially along the Riva degli Schiavoni. There is an excellent overview of the district and its function in the city here.

Get one free guide map here (see the Arsenale link below).  You can download 6 free walking maps all at once here, and another 6 free maps if you subscribe here.