Zaragoza is a city in northern Spain where eight Spanish Assassins were being held during the Renaissance, two of whom died. Ezio Auditore rushed there to free them. At the time of the Spanish Inquisition it was located in the Kingdom of Aragon.
After having travelled to Barcelona and finding a list of names on Gaspar Martínez' body, Ezio Auditore and Raphael Sánchez made their way to Zaragoza to save the Assassins that were still threatened by the Spanish Inquisition.
Raphale advised Ezio to seek out Pedro Llorente, the man who was to oversee the execution of the Assassins. Ezio quickly managed to find him, and overheard a conversation between him and Tomás de Torquemada, who subsequently ordered the execution of the first Assassin and revealed he was working on orders of Rodrigo Borgia.
Ezio then made his way through the city to save the remaining Assassins, causing Llorente to double the security on the last prisoner. However, Ezio managed to free him as well and decided to assassinate Llorente. Upon their confrontation, Llorente revealed not to believe in the Templars, but Ezio assassinated him nonetheless, as he had acted as an unknowing ally to them.
Soon after the successful assassination, Ezio and Raphael made their way to Granada to further weaken the Templars.