Built in the 13th Century by the overlords of Siena, Monteriggioni was actively involved in the defence of Tuscany against Florentine attempts to gain more territory. At the front of this conflict was the Auditore family, who became the city's rulers and protectors. It was the Auditore who constructed Monteriggioni's famous walls, which can still be seen today.
Although standing in opposition to Florentine desires, the Auditore had cordial relations with the Medici family, largely due to their collective Florentine roots.
Monteriggioni successfully withstood attacks from Florence, until in 1554, the city was betrayed. Giovannino Zeti, the keeper of the garrison and a Florentine exile, was allowed to return to Florence in exchange for the keys to the city.
Extraordinarily, the Auditore were allowed to continue their rule of Monteriggioni under Florentine leadership, showing that the Medici do not forget their friends.