The 70-year-old actor said he was overwhelmed with the beauty of the capital city of the Italian region of Tuscany as well as the honour bestowed on him.
"Overwhelmed as I am with the beauty and elegance of Firenze, the opening of the River to River 12 India Film Festival tonight at the Odeon Cinema, one of its oldest is a delight to be present at, where the Deputy Mayor of the City, with his designated sash or ribbon of honour around his shoulder, presents me with the keys of the City of Firenze, and invites me to the city again not as a tourist but as a guest.
"Nothing could have been more overwhelming than this recognition, in the presence of the Ambassador to Italy of India and other distinguished guests," Bachchan wrote on his blog.
The seven day film extravaganza will also have a retrospective of Bachchan, where his films like "Deewar", "Black" and "Sholay" will be screened.
'Everlasting Light', a documentary on the life and career of Big B by Ram Madhvani, will also be screened at the fest.