The external decoration in white and pink marble lozenges (adapted from Arezzo Cathedral) was never completed; a trial section can still be seen on the main façade.

Until the end of the nineteenth century the statue was more prominently placed in the Piazza Danti (square), but it was repositioned to the side in order to make way for the electric tram which was inaugurated in 1899.

In the unfinished wall is a portal designed by Galeazzo Alessi (1568), a pulpit composed of ancient fragments and Cosmatesque mosaics, from which Saint Bernardino of Siena preached in 1425 and 1427 and a wooden Crucifix by Polidoro Ciburri (1540).

It also houses a reliquary by Bino di Pietro and Federico and Cesarino del Roscetto, considered amongst the masterworks of Italian Renaissance goldsmiths' work.

Continuing on the side wall are the remains of an altar by Agostino di Duccio (1473), demolished in 1623. Notable is the apse, with a wooden choir with intarsia by Giuliano da Maiano and Domenico del Tasso (1486–91), which was damaged by a fire in 1985.

Two small side doors lead to Oratory of St. Onofrio, built to house altarpiece with the same name by Luca Signorelli, now in the Cathedral Museum.