The Castello District was a district in Venice located to the east of the Palazzo Ducale. The largest district of Venice, activity in the district was centered around the Arsenale di Venezia, which housed an abundance of soldiers.
- Quartier di Bartolomeo d'Alviano: Headquarters of the Venetian mercenaries, and the home of their leader, Bartolomeo d'Alviano.
- Arsenale di Venezia: The arsenal base in Venice at which Ezio Auditore assassinated Dante Moro and Silvio Babarigo. The Arsenale base is also home to one of the three Templar Lairs within Italy.
- Silvio Barbarigo Il Rosso: Member of the Supreme Tribunal of Venice.
- Dante Moro: Personal bodyguard of Silvio and Marco Barbarigo.