In Assassin's Creed II, Ezio Auditore's family hometown in Tuscany is Monteriggioni.
Monteriggioni is introduced as the Auditore family's ancestral home and a fortified settlement in the Italian countryside. After Ezio's family is targeted in Florence, he travels there with his sister Claudia and mother Maria, joining his uncle Mario Auditore.
The game uses Monteriggioni as a recurring base rather than merely a brief story location. Ezio can renovate buildings, improve the town's income, and return there between missions. This makes the settlement important to the game's economic and progression systems.
Monteriggioni is a real medieval walled town in Tuscany, near Siena. It is not the same place as Florence, where much of Ezio's early story occurs, or Rome, which becomes central in Assassin's Creed: Brotherhood.