Dating back to the twelfth century, it was one of two gates originally used by famous people and official representatives to access the city (the other was the Gate of Parlascio). Leading directly to the religious center of the city, the gate was symbol of its power. The name is due to the marble lion (probably Etruscan) initially placed outside in a niche as a protector of the city. 

Being Pisans and Florentines commercial and political competitors, once the latter occupied the city, the lion was moved over the walls, facing the city, no more as an overseer of Pisa, but to watch over the city and control it. Along with the towers severed, it was a symbolic way to make the Pisans fly down. Moreover, just outside the door the Jewish community was granted to build its own graveyard, thus making the passage completely inaccessible.

Later on, the Florentines built a new gate to access the square: Porta Nuova.