Monteriggioni serves as the main Assassin headquarters in Assassin's Creed II.
In the game, Ezio Auditore reaches the Tuscan hill town with his uncle Mario after fleeing Florence. Mario has converted the Auditore family villa into a fortified base for the Assassin resistance. Players can renovate the town, improve shops and buildings, and use the villa as a central location between missions.
Monteriggioni is a real medieval walled settlement in Tuscany, near Siena, rather than a city invented entirely for the game. Assassin's Creed II also features major historical cities such as Florence and Venice, which can make the headquarters easy to misidentify. The real town was founded by the Republic of Siena in 1213 and is known for its preserved defensive walls and towers.