The San Gallo Gate was begun according to the plans of Arnolfo di Cambio in 1284, but was not completed until 1327.

[1] In the 13th century, it was one of the most heavily trafficked gates in the city, as it was the most northerly, connected to the road to Bologna.

[2] On the gate, whose keys are still kept in the local history section of Palazzo Vecchio, an inscription recalls the foundation of the building in 1285 by the captain of the Guelph party Rolandino da Canossa, while another, later, celebrates the passage of King Frederick IV of Denmark in 1708, on his journey to Venice.

[3] The exterior is decorated with Marzocco while the interior lunette contains traces of a fresco depicting the Madonna and saints.

[5] It is also outside this gate, in the stony bed of the Mugnone that served as a moat, that Calandrino's search for the Heliotrope (Boccaccio, Decameron VIII, 3) is set.