What is the name of the Assassin order's headquarters in Assassin's Creed II?

The Assassin order's headquarters in Assassin's Creed II is Villa Auditore.

Villa Auditore is Ezio's family estate in the Tuscan town of Monteriggioni. After leaving Florence, Ezio and his allies use the villa as a base while its surrounding property is gradually restored and developed.

The villa becomes more than a residence: it functions as a management hub where players can upgrade buildings, display collected items, and receive information about the family's history. Its growth reflects Ezio's increasing resources and influence.

Monteriggioni is the town, while Villa Auditore is the specific estate. The nearby fortress-like setting can also lead to the informal label “Monteriggioni Castle,” but that is not the canonical name used for Ezio's family villa.