In the lunette over the door is a glazed terracotta sculpture by Andrea della Robbia depicting the Madonna with Saints Stephen and John.

Internally, the church, built on a Latin cross ground plan, has a nave and two side aisles, all in Romanesque style and dating from the early 13th century.

It is faced, in the opposite aisle, by a great bronze candelabrum by Maso di Bartolomeo (1440), having an elongated vase-shape from which seven branches protrude.

Maso also executed the balcony of the inner west wall, which in addition is decorated with a fresco of the Assumption by David and Ridolfo del Ghirlandaio.

A small staircase leads from the old church to the 14th-century transept, which has five high cross vaults, each ending in an apse divided by pilasters.

In the south arm of the transept is the Renaissance tabernacle by the Da Maiano brothers: the Madonna with Child terracotta (1480) is by the more famous Benedetto.

Next is the Assumption Chapel, which was frescoed in 1435-1436 by the so-called Master of Prato and by a young Paolo Uccello, who painted the Stories of the Virgin and St. Stephen, completed by Andrea di Giusto in the lower section.

They show a bizarre fantasy of enchanted figures caught in a wide range of brilliant colors, and surrounded by Brunelleschi-like architectures.

On the lower north wall are depicted the Obsequies of St. Stephen, in which Lippi portrayed Pope Pius II, set in a Palaeo-Christian basilica, as an imposing figure in scarlet costume.

On the opposite wall is Herod's Banquet, showing a large hall in which Salome is performing her ballet, and the handing over of the head of John the Baptist to Herodias.