Located in the northern part of the ancient village, it was also known in the 14th century as Porta Bandinellorum, and is the only remaining urban gate in Asciano. Documented as early as 1338, it represented the main access point towards Siena.

The gate current appearance is the result of extensive remodeling that took place after 1773, the year in which a drawing still showed its original configuration, incorporated into a defensive tower. The modern intervention radically altered the medieval structure, leaving today a simple semicircular arch made from reclaimed materials, including stone and brick.

Above the arch are three coats of arms:

• The Balzana Senese, symbol of the Republic of Siena

• The municipal coat of arms of Asciano, featuring a lion’s paw holding an axe

• The coat of arms of the Bandinelli family, from which the gate ancient name derives

In 1868, Cavaliere Carlo Bianchi, owner of nearby lands, proposed demolishing the gate to replace it with a "barrier." The initiative was not accepted, but in 1873 Bianchi renewed his request due to the poor condition of the arch. Although there are no definitive documents about the outcome, an evaluation for a possible restoration dated 1900 is preserved.

Today, despite the transformations, the Porta del Bianchi remains an important historical testimony to Asciano’s medieval urban layout.