On the inside of the façade, at the sides of the main doorway, there are two frescoes, one by Paolo Uccello and the other by Andrea del Castagno. In the past, these frescoes were detached and taken to a different location.

Today they are back in their original locations again.
The man on horseback is the English commander, John Hawkwood known, in the Florence of the day, as Giovanni Acuto, The fresco was painted in 1436 by Paolo Uccello and is his first Renaissance work. He studied carefully how to create the foreshortening necessary to gain the right perspective, and he chose prevalently green tones in order to achieve the effect of a bronze statue. The other fresco, by Andrea del Castagno, is dated 1456 and celebrates another man of arms, Niccolò da Tolentino. The figure is painted on false marble and is portrayed with great expressive force.
As you go further into the Cathedral, up towards the dome, you will see on the left hand side a painting made in 1465 by Domenico di Michelino. It shows Dante with the book of his Divine Comedy radiating light on the city of Florence.